The European Union may have to delay lifting its arms embargo on China, British officials said on Tuesday.
China's policy on Taiwan is causing concern
They pointed to comments by UK Foreign Secretary Jack Straw, who said China's passing of a law against Taiwan secession had made it "more difficult".
The arms ban, imposed after the 1989 Tiananmen massacre, was widely expected to be lifted later this year.
But the US has stepped up its criticism of the move, which it fears could fuel the arms race between China and Taiwan.
France and Germany are keen to lift the embargo and replace it with a strengthened code of conduct on all EU arms sales. Britain, which takes over the six month EU presidency on 1 July, has given its support in principle.
But the BBC News Website's World Affairs correspondent, Paul Reynolds, says the British government now appears reluctant to have the embargo lifted while it is holding the EU presidency.
A decision during that time might embarrass British Prime Minister Tony Blair, a close ally of US President Bush, our correspondent says.
British Foreign Secretary Jack Straw said at the weekend that the problems of lifting the embargo had recently become "more difficult rather than less difficult".
He said that Beijing's recent passage of a law allowing China to use military force against Taiwan if it moved towards declaring independence had created "a difficult political environment" that was complicating the lifting of the arms ban.
Ending her visit to Beijing on Monday, US Secretary of State Condoleezza Rice said Mr Straw's "sobering comments" reinforced Washington's concern that lifting the embargo would alter the balance of military forces in the region.
The US has always opposed the lifting of the ban, warning that China could embark on an arms-buying spree.
Because the US might help defend Taiwan in the event of an attack by China, it does not want anything to add to Chinese capabilities.
British officials denied US reports that the EU had already decided to put off consideration of lifting the embargo until next year.