LONDON (Reuters) - The British government on Thursday looked set to limit the length of an upcoming strike by nurses, after their trade union did not send lawyers to defend legal action it has brought over the dispute.

The Royal College of Nursing (RCN) has called a 48-hour strike from the evening of April 30, which for the first time would involve staff from emergency departments, intensive care units, cancer care and other services that were previously exempt.

However, Britain's health department says that industrial action on May 2 would be unlawful because a vote to strike is only valid for six months after a ballot of trade union members.

Lawyers representing health minister Steve Barclay told London's High Court on Thursday that, as the RCN ballot closed on Nov. 2 last year, a strike on May 2 would be "clearly unlawful action".

The RCN did not send lawyers to the hearing.

Lawyer Andrew Burns, representing the government, said the union had performed "a significant U-turn" and was no longer contesting the bid to have the final day of its strike action declared unlawful.

"We have ended up in a very regrettable situation where a major – and, one would hope, responsible – trade union has been publicly saying that its members can take lawful strike action on May 2," Burns said.

A ruling on the government's application is expected on Thursday afternoon.

RCN General Secretary Pat Cullen, speaking outside court before the hearing, said it was a "sad day".

"Steve Barclay may get a legal win today, but what he has done is he has lost the public and he has certainly lost nursing, so it is a short-term gain," she said.

(Reporting by Sam Tobin; editing by Michael Holden)