The government warned on Sunday that British troops' lives could be sacrificed, as Tony Blair stepped up preparations for a joint military operation with the US against terror networks in Afghanistan.

Mr Blair called more than 40 senior MPs to Downing Street on Monday to brief them on his trip to Washington and consultations with world leaders - a sign of advanced planning for military strikes.

He will meet members of the Commons foreign affairs, defence and home affairs committees, and the parliamentary intelligence and security committee. He will also meet the parliamentary Labour party's liaison committee - vital for keeping his own backbenchers onside.

"Just as building an international consensus is very important, the prime minister wants to build a coalition inside this country supporting the response which will come in due course," said Downing Street.

John Reid, Northern Ireland secretary, asked on BBC1's Breakfast With Frost whether there would be casualties, said: "I think we have to accept that . . . We should not avoid the proposition that there will be danger to us, we are America's biggest ally, and it may involve sacrifices not only here at home, with inconvenience and possible danger.

"In standing up to terrorism there is the danger of sacrifices of lives, because to do anything other is to say that we will avoid the difficulties and the chances of sacrifice and essentially capitulate to terrorism."

Monday's meetings may forestall pressure, voiced on Sunday by Labour's Tam Dalyell and the Tories' John Redwood, for parliament to be recalled. Whitehall officials said there were no plans to do so this week.

There is speculation that Labour's conference, to open next Sunday in Brighton, could be shortened if forces were in action. "We are taking it a day at a time," a senior Labour figure said.

Bernard Jenkin, shadow defence secretary, told GMTV that while British forces would be "very capably involved", soldiers were not getting enough leave or training with live equipment.