"Great Britain could be more helpful than it has been in support of US policies that would prevent Iran from acquiring nuclear weapons," Senator Jon Kyl, the Senate's number two Republican, told AFP.

"I appreciate that this economic crisis is very much on the minds of people both in Great Britain and the US, but strategically there are things we need to do to work together and I don't like to see them ignored," he said.

Kyl said Britain, a key US partner in putting diplomatic pressure on Tehran over its suspect nuclear program, was not doing enough to help Washington pile economic pressure on the Islamic republic.

He urged Brown to consider stepping up efforts to restrict banking relationships with Iran, either by helping to punish banks that do business in Iran or banks that work with banks that do business there.

"There's been some cooperation there with Great Britain and some of the other countries. There could be more," he said.

"While there is a great strategic relationship between us, I would hope that maybe he would be willing to address what Great Britain could do to assist us," during his visit to Washington, he said.

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