LONDON — The prospect of an imminent Western military strike on Syrian government targets appeared to encounter a delay on Wednesday when Britain signaled it would first await the findings of a United Nations inquiry into the suspected use of chemical weapons in an attack that killed hundreds near Damascus last week, and then hold a separate parliamentary vote, which could be days away.

Prime Minister David Cameron of Britain, who runs a coalition government, is facing political difficulties from legislators mindful of the experience in Iraq, when assurances from Prime Minister Tony Blair and President George W. Bush that Saddam Hussein had weapons of mass destruction proved inaccurate and a false pretext for war.

Mr. Cameron bowed on Wednesday to pressure from the opposition Labour Party and to some within his own coalition who want to allow United Nations weapons inspectors a chance to report their findings and for the United Nations Security Council to make one more effort to give a more solid legal backing to military action against Damascus.

As Mr. Cameron ran into difficulties, the Syrian government, which has denied accusations by a range of Western and Arab countries that it used chemical weapons in the Aug. 21 attack, moved abruptly to prolong the inspectors’ visit, announcing that it had evidence of three previously unreported chemical weapons assaults that it said had been carried out by insurgents and should be investigated by the inspectors.