Earlier claims that all the oil had been collected were incorrect, an Environment Ministry spokesman said.
Latvia's Environment Minister Vladimirs Makarovs sent a letter to his Lithuanian counterpart protesting at a lack of information from Lithuania, and complaining of Lithuania's "illicit" use of chemical sprays in Latvian territorial waters, which he described as a "breach of international relations."
A peaceful demonstration by about 20 members of Latvia's Environmental Protection Club outside the Lithuanian Embassy in Riga ended in the arrest of the club's president, Arvids Ulme.
Hoses carrying oil aboard the Norwegian-registered tanker North Pacific became detached when the ship broke free of its moorings during bad weather, said terminal operator Mazeikiu Nafta. The U.S. company Williams International owns a 33 percent stake in Mazeikiu.
Felikss Klagiss, head of Latvia's Marine Control Division in Riga, said it took 16 hours for clean-up work to begin due to the distance between Butinge and emergency equipment based in the port city of Klaipeda.
The booms with which Mazeikiu first attempted to collect the oil were ineffective, he said.
"These booms only work when waves are less than a meter high. On our inspection flight two days after the accident we saw a very different picture from what we'd been led to believe. The oil slick was one square kilometer in size, equaling around 740 liters of oil, probably only 10 percent of what was spilled. The rest would have dissolved or sunk to the sea bed."
In his letter, Makarovs called for stricter requirements concerning weather conditions in which oil can be loaded. He highlighted the lack of facilities at Butinge for receiving waste such as sludge and tank-washing water, which the ministry says is often dumped at sea. He also called on Lithuania to sign an agreement with Latvia which would regulate management of oil spills and payment of compensation.
Kasparas Jonasauskas, press secretary at the Lithuanian Environment Ministry, acknowledged that there had been "a very bad lack of information between the countries," a problem which should be addressed, he said.
The ministry had been "surprised" by Mazeikiu Nafta's use of Simple Green, a water treatment chemical which the Helsinki Commission on Environmental Protection considers inappropriate for use in closed seas such as the Baltic. The need to act quickly had overridden the necessity of informing the Latvian authorities, said Jonasau-skas. The ministry had also been surprised to hear that Mazeikiu had not stopped loading operations during the storm.
"We have some criticisms of Mazeikiu Nafta. We must prevent these problems occurring in future," he added.
The direction of currents in the area means Latvia is most at risk from accidents at Butinge. The area north of the terminal is a spawning ground for herring and sprat, and the beach at Liepaja is a popular tourist attraction. Latvian authorities opposed the building of the terminal, which opened in 1999. Anger intensified when oil sludge washed up on Latvian beaches following an accident similar to last week's, in December 1999.
David Matulionis, spokesman for Prime Minister Rolandas Paksas, criticized what he called an "overly politicized" atmosphere surrounding Butinge.
"Let's not lecture each other. We must sit down and discuss how to do everything possible to eliminate future accidents."
Tadas Augustauskas, spokesman for Mazeikiu Nafta, said the company would do everything possible to make its operations safe. The clean-up operation had been effective and there would be no damage to Latvia's coast, he said. "We understand the shadow this casts over Mazeikiu Nafta. We're keen to find the cause of the problem. We understand we have to take responsibility."
Latvian municipal authorities have been alerted to the possibility of oil washing up on their beaches, said Klagiss.
"They're ready to start collecting," he said. "There is a special budget to pay for such operations."
Municipal police in Riga charged Arvids Ulme of the Environmental Protection Club with organizing an unsanctioned demonstration. He was released pending a trial. The club's press secretary Janis Ulme said: "We just demonstrated. We can't predict when the next oil spill will be."
Alice Babre, a 17-year-old banner carrying student said: "We're neighbors, but not everything is right between Latvia and Lithuania."
There have been strong reactions in Latvia against Lithuania's Butinge oil terminal and the recent oil spill there. In Lithuania, people are defensive of their country's new oil facility. To gauge what people think of recent events at Butinge, The Baltic Times went out in the streets and asked.
Normunds, railway engineer
Oil is big business. We have our own oil terminal at Ventspils but it's safer. I don't think the Butinge terminal is important for Lithuania. If we join the European Union, one oil terminal in the Baltics will be enough. The oil spillage will be very dangerous for our sea since it's like a lake.
Ilze, head of the state social insurance statistics department
Of course I think the terminal is a problem, not only for Latvia, but for all states around the Baltic Sea that are close to it. I think the oil spill will be very dangerous for the Latvian shores.
I think this terminal is very bad for Latvia, because wind and water currents will bring any oil spills in our direction. The terminal means very big money, not for Lithuania, but for businessmen.
Greta, architecture student
I've seen the terminal and the oil, and I think it's disgusting. What the Butinge terminal representatives say about the terminal, and what the reality is are not the same. I don't know what the oil will do to the birds and fish, but I don't think it will be nice.
The oil industry is necessary for Lithuania, which is why the Butinge terminal is extremely important. I think the pollution of the natural environment will be minimal, and such minor accidents are unavoidable.
Butinge cannot be closed, because it provides a lot of profit. More financial resources should be given to increase its security. Green activists in Latvia will change nothing. They just escalate tension between both nations.
The security of such an asset should be of primary importance. But the drastic behavior of the Latvians is surprising. Their decision to cross the border illegally in a helicopter was a big mistake. International agreements should be followed in all cases. I think Lithuania will compensate for any ecological damage.
Butinge is close to the Latvian border, and it's obvious that this is a threat to Latvian nature. But there are lots of huge industrial objects in the world that are close to borders. Butinge had to be built near the Mazeikiai oil refinery.