This dispute has caused some harm to bilateral economic relations - that's undeniable

US Ambassador Alexander Vershbow

But analysts viewed the Russian embargo as a tit-for-tat move after Washington introduced tariffs of up to 30% on US steel imports.

US Ambassador Alexander Vershbow said he signed a protocol agreement under which the US agreed to exclude temporarily 14 poultry plants from a list of exporters, pending inspection of sanitary conditions.

The US also agreed to provide assurances against counterfeit veterinary certificates and the ban will now be lifted by 10 April.

Mr Vershbow said: "With the visit of President Bush just two months away, we need to start working to expand our areas of co-operation now that this obstacle appears to have been removed."

He said: "This dispute has caused some harm to bilateral economic relations - that's undeniable."

Summit difficulties

US poultry sales to Russia, which make up about 40% of all US poultry exports, are worth between $600m and $800m each year.

It has engaged at least five cabinet ministers on my side, and even President George W Bush, who has spoken to President Putin directly about this

US Ambassador Alexander Vershbow

"This dispute has become the number one problem in the US-Russia relations in the past month," Mr Vershbow said.

"It has engaged at least five cabinet ministers on my side, and even President George W Bush, who has spoken to President Putin directly about this."

The ban was one of several difficulties affecting relations ahead of the 23-26 May summit in Moscow and St Petersburg.

Other differences focus on attempts to clinch an accord on slashing strategic nuclear arsenals, with Russia suspicious of US plans to store rather than destroy warheads.

Cut-price US chicken legs flooded the Russian market in the early 1990s during the presidency of George Bush, the current president's father, and were dubbed "Bush legs".