Britain's opposition Labour Party has lost a vote to try to force Theresa May to change her austerity agenda and increase public sector pay, in the first of many expected challenges to the prime minister's ability to govern.

May won by 323 votes to 309 in the first parliamentary vote since she secured the backing of a small Northern Irish party to give her a narrow majority in parliament. She lost her overall majority in an early election she called on June 8, a failed gamble that has cost her much of her authority.

The British leader took no chances on Wednesday. Her foreign minister, Boris Johnson, was called back for the vote from Switzerland, where he was leading the British delegation in peace talks for the divided country of Cyprus. It was not clear whether he got back in time to vote.

May has come under fire from inside and outside her Conservative party over her strategy for Britain's departure from the European Union and has been forced to scrap many of her planned reforms.

Under leftist leader Jeremy Corbyn, Labour had been expected to lose seats on June 8 but instead made gains. It is strongly attacking public spending cuts, blamed by some for a fire two weeks ago that killed at least 80 people in a London social housing block.

The failed Labour amendment challenged a cap on public sector pay rises of a below-inflation one per cent a year, as the government seeks to reduce its budget deficit.

"You can't have safety and security on the cheap. It is plain to see that seven years of cuts to our emergency services has made us less safe; it's time to make a change," Corbyn said in a statement before the vote.