British voters went to the polls to choose thousands of new local councillors, with the outcome set to be closely watched for proof of the strength of May's Conservatives ahead of the June 8 parliamentary elections.
Polling stations closed at 10:00pm (2100 GMT) with results due throughout Friday to determine nearly 5,000 local authority seats across England, Scotland and Wales, along with eight metropolitan mayoralties.
Experts caution against using the results to predict the outcome of next month's vote, as they are typically fought on local issues.
But the proximity of the general election and the increasingly hostile atmosphere between London and Brussels over the Brexit negotiations overshadowed Thursday's polls.
'Threats against Britain'
Acting on last year's referendum, May gave the European Union formal notice of Britain's intention to leave the bloc on March 29, and two weeks ago called a surprise general election.
She says she wants to strengthen her mandate as she heads into the Brexit negotiations.
Speaking outside her Downing Street office on the eve of the local polls, May blasted Brussels for making "threats against Britain" over the divorce proceedings.
The two sides have clashed over the costs of leaving, prompting May to accuse the EU of toughening its stance in statements "deliberately timed to affect the result of the general election".
European Parliament President Antonio Tajani dismissed the claim, insisting: "No one is trying to influence the outcome."
German Finance Minister Wolfgang Schaeuble meanwhile weighed in with a warning of tough times ahead.
"The negotiations will become terribly difficult for the UK, they will see it," he told a reception at South Africa's University of Kwazulu-Natal, on the sidelines of the World Economic Forum in Durban.
And EU President Donald Tusk said that early rows over Brexit risked the entire process.
"These negotiations are difficult enough as they are. If we start arguing before they even begin they will become impossible," he told a news conference.
"The stakes are too high to let our emotions get out of hand," he added.
But the EU fired a fresh salvo on Thursday, proposing new rules that would require a huge slice of London's vital banking business to leave the UK after Brexit.
Unveiled by European Commission vice-president Valdis Dombrovskis, the rules would deny London the right to host banking "clearing houses" that deal in euros, the EU's single currency.
Local elections spillover
British opposition leaders have claimed May is using the EU talks as a distraction from other issues, with Labour chief Jeremy Corbyn accusing her of "playing party games with Brexit".
A YouGov poll of 2,066 adults on Tuesday and Wednesday for The Times newspaper put the Conservatives on 48 percent, Labour on 29, the Liberal Democrats on 10 and the UK Independence Party on five ahead of the general election.
Labour says the local election results could show the huge gap could be inaccurate.
"Let's see what happens. That might be an interesting measure of how things are going more generally, and how accurate the polling is," a senior Labour source said.
Roger Scully, a politics professor at the University of Cardiff, said national issues would inevitably have some effect on the outcome of Thursday's vote.
"The Conservatives are doing very well and that is almost certainly likely to have some spillover into the local elections," he said.
"They will provide some vital information about the pattern of support and where parties are performing particularly strongly or weakly," added Anthony Wells of YouGov.
The smaller, pro-EU Liberal Democrats are hoping to garner some momentum for the June vote with gains on Thursday.
By contrast the anti-EU, anti-mass immigration UK Independence Party is predicted to lose most of its council seats as it struggles to define itself now that its principal goal -- Brexit -- is on its way to being achieved.
(This story has not been edited by NDTV staff and is auto-generated from a syndicated feed.)
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