Britain's House of Commons briefly suspended Wednesday's session and members evacuated the chamber after an object containing purple powder was thrown from a public gallery and hit Prime Minister Tony Blair.

Witnesses say a well-dressed young man threw the object at Mr. Blair from a section of the gallery reserved for distinguished guests. The object hit Mr. Blair in the back and lawmakers brushed the powder off his clothing as others rushed him from the chamber. Officials say Mr. Blair was not injured and later confirmed that the substance in question was harmless.

Authorities arrested two people in the gallery. The incident occurred during the weekly period when the prime minister appears in parliament to answer lawmakers' questions.

A group calling itself "Fathers for Justice" which campaigns on child custody issues, claimed responsibility for the disruption.

The incident occurred just weeks after authorities installed a screen in front of the public gallery to prevent such incidents. But the two men had been in an unscreened section reserved for guests signed in by members of parliament or the House of Lords.