UPDATE 1-Britain's May seeks deal to cling to power

* Weakened PM May seeks deal with Northern Irish party

* DUP could support minority Conservative government

* Opposition leader Corbyn says he could take power

* Turmoil overshadows planned start of Brexit talks (Adds Corbyn, Conservatives challengers, other details)

LONDON, June 11 (Reuters) - British Prime Minister Theresa May was seeking a deal with a small Northern Irish party on Sunday to stay in power after losing her party's parliamentary majority in a catastrophic electoral gamble just days before Brexit talks are set to start.

But with May's personal authority in tatters, there were reports that moves were afoot within her Conservative Party to dislodge her, while opposition Labour leader Jeremy Corbyn was insisting she could be ousted and he could replace her.

May's Downing Street office said on Sunday she had spoken with Northern Ireland's pro-Brexit, socially conservative Democratic Unionist Party (DUP) to discuss finalising a deal when parliament returns on Tuesday.

"We will welcome any such deal being agreed, as it will provide the stability and certainty the whole country requires as we embark on Brexit and beyond," Downing Street said in a statement.

"As and when details are finalised both parties will put them forward," it said.

The timing is challenging, with Britain due to start negotiating the terms of its exit from the European Union with the bloc's 27 other members on June 19.

The Conservatives won 318 House of Commons seats in Thursday's election, eight short of an outright majority. Labour, the main opposition party, won 262. The DUP won 10.

Labour's Corbyn told the Sunday Mirror newspaper he saw a route to power himself, although it was not clear how he would command the support of a majority of members of parliament.

Labour's tally, even when added to those of potential allies such as the Scottish National Party and other smaller parties, was still short of a majority.

"I can still be prime minister. This is still on. Absolutely," Corbyn was quoted as saying.

He said his party would seek to vote down May's Queen's Speech, or programme for government, when she presented it to parliament. If that succeeded, May would be expected to stand aside and let Corbyn try to win the backing of a majority of members of parliament to form a government.


May had called the snap election with a view to increasing the narrow majority she had inherited from her predecessor David Cameron. At the start of the campaign, she was enjoying poll leads of 20 points or more over the main opposition Labour Party.

But after a poor campaign and an unexpectedly stiff challenge from Labour, her plan went disastrously wrong, leaving her unable to form a sustainable government without DUP support.

"I don't think Theresa May and this government have any credibility. The prime minister called this election on the basis she would need a stronger mandate to negotiate Brexit. Well, look what's happened," Corbyn told the Sunday Mirror.

The Conservatives now plan to reach a so-called confidence and supply agreement with the DUP, which would involve it supporting a Conservative minority government on key votes in parliament but not forming a formal coalition.

After an initial round of discussions, Downing Street had said on Saturday that the "principles of an outline agreement" had been agreed with the DUP.

The DUP itself later issued a statement saying the talks had been positive, but stopped short of confirming a deal had been sealed.

"The DUP today (Saturday) held discussions with representatives of the Conservative Party in line with Arlene Foster's commitment to explore how we might bring stability to the nation at this time of great challenge," the party said.

"The talks so far have been positive. Discussions will continue next week to work on the details and to reach agreement on arrangements for the new parliament."

While that to-and-fro was unfolding, several British newspapers were reporting that some prominent Conservatives, including Foreign Secretary Boris Johnson and Brexit minister David Davis, were being urged by supporters to challenge May for the party leadership.

Johnson dismissed the reports as "tripe", tweeting late on Saturday that he was backing May. (Additional reporting by Conor Humphries in Dublin, writing by Estelle Shirbon; Editing by Jason Neely and Keith Weir)