The US has said the success of a move by oil giant BP to curb¹ a leak in the Gulf² of Mexico is "not clear" and the technique provides "no solution".

美国官员称，石油巨头英国石油公司在墨西哥湾阻止原油泄露的一次行动结果“未明”，其使用的技术“没有产生效果”。

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A boom is erected in Louisiana to counter the spill

It was responding to BP's move to siphon（抽取） oil from the leaking well head to a tanker⁴ on the surface.

A government statement said it would not rest until the leak was permanently⁵ sealed and the spill（溢出，溅出） cleaned up.

BP executive Kent Wells earlier said that the siphoning process was "working extremely well".

This was the third attempt it had made to insert a long narrow tube into the leaking pipe, using underwater robots.

It is thought that BP's 6in-wide (15cm) tube and stopper could capture more than three-quarters of the leak, although a smaller spill nearby also has to be contained.

Mr Wells said on Sunday at the firm's US headquarters in Houston, Texas, that over the next few days the company planned to slowly increase the amount of oil and gas flowing through the pipe to the tanker.

Commitments

But a joint⁷ statement by Secretary of Homeland Security Janet Napolitano and Secretary of the Interior Ken⁶ Salazar said the latest technique was "not a solution to the problem and it is not yet clear how successful it may be".

It added: "We will not rest until BP permanently seals the well head, the spill is cleaned up, and the communities and natural resources of the Gulf Coast are restored and made whole."

It was the second strong statement to BP by the government officials on the current crisis.

Earlier they sent a letter saying they wanted to be sure BP would honour commitments not to limit costs to a US statutory（法定的） cap of $75m (£50m).

BP responded by saying it had already made clear its position on paying damages for the disaster.

It said last week the cap was irrelevant⁸（不切题的，不相干的） and it would settle all legitimate⁹（合法的，正当的） damages claims.

"What they are requesting in the letter is absolutely consistent with（与……一致） all our public statements on the matter," said BP spokesman David Nicholas on Sunday.