A person walks past an EU and a British flag in London, Britain, April 2, 2019. REUTERS/Hannah Mckay

LONDON (Reuters) - Lawmakers risk tying the hands of Prime Minister Theresa May in negotiations if they pass a bill that will force her to seek a further Brexit delay to stop Britain leaving the European Union on April 12 without a deal, her spokesman said on Thursday.

The spokesman said the bill, being debated on Thursday in the upper house of parliament, could in fact raise the risk of a no-deal Brexit.

“We are disappointed that MPs (members of parliament) have chosen to back the bill. The prime minister has already set out a clear process through which we can leave the European Union with a deal and we have already committed to seeking a further extension,” the spokesman told reporters.

“If passed ... this bill would place a severe constraint on the government’s ability to negotiate an extension and reflect this new date in UK statute books by April 12.”