The role of an opposition should be to challenge the government, but Britain's Labour Party has begun the new year at war with itself as leader Jeremy Corbyn struggles to assert his authority over restive lawmakers.

The veteran left-winger was the surprise winner of Labour's leadership election last year, strongly supported by the party's membership but less so by Labour's lawmakers.

He has clashed with centrists over issues including his opposition to nuclear weapons and to British airstrikes on IS targets in Syria.

Early Wednesday Corbyn moved defense spokeswoman Maria Eagle, who opposed him on nuclear weapons, to another post, and fired two other members of his team who had criticized him.

Legislator Jonathan Reynolds later resigned as Labour's railway spokesman, saying he wanted more freedom to speak out.