Image copyright Getty Images Image caption Opposition parties say they will not back the prime minister's call for an election - left to right: Jo Swinson, Jeremy Corbyn, Liz Saville Roberts and Ian Blackford

UK opposition parties have agreed not to back Boris Johnson's demand for a general election before the EU summit in mid-October.

Labour, the Lib Dems, the SNP and Plaid Cymru say they will vote against the government or abstain in Monday's vote on whether to hold a snap poll.

But the PM said the parties were making an "extraordinary political mistake".

Meanwhile, a bill designed to prevent a no-deal Brexit has been approved by the House of Lords and will pass into law.

It will force the prime minister to ask the EU for the Brexit deadline to be extended beyond 31 October if no deal is agreed by the UK and Brussels by 19 October.

Mr Johnson wants an election to take place on 15 October, ahead of that date and the EU summit on 17 and 18 October.

He argues that a snap poll will allow the government to "get on" with delivering Brexit by the end of October.

But opposition MPs - who, along with Conservative rebels, have already defeated one attempt by the government to bring in an early election - say Mr Johnson is trying to push through a no-deal exit.

Media playback is unsupported on your device Media caption Johnson: Parliamentarians trying to block Brexit

During the past week the prime minister has suffered several defeats over Brexit in Parliament, expelled 21 of his own MPs for rebelling and seen his younger brother, Jo Johnson, resign from government.

In other developments:

Mr Johnson's decision to prorogue - suspend - Parliament next week ahead of a Queen's Speech on 14 October is being challenged in the courts in Scotland and Northern Ireland. Scotland's Court of Session will give its judgement next week.

Campaigner Gina Miller has lost a judicial review she brought to London's High Court over the prorogation. However, permission has been granted for the case to be heard in the UK Supreme Court on 17 September.

The chief constable of West Yorkshire said he was "disappointed" his officers were used as a backdrop to a speech by Boris Johnson about Brexit in Wakefield.

Following the meeting of opposition parties on Friday, a Labour Party spokesman said: "Jeremy Corbyn hosted a positive conference call with other opposition party leaders this morning.

"They discussed advancing efforts to prevent a damaging no-deal Brexit and hold a general election once that is secured."

Does PM have a cunning plan?

Image copyright AFP

By John Pienaar, BBC deputy political editor

As good weeks go, for Boris Johnson this wasn't one.

Defeated and defeated again in the Commons, choosing to sack more than 20 of his most respected though rebellious colleagues - provoking uproar from Tories who say that was brutally heavy-handed, and now trying to sound conciliatory.

The list of Tory MPs standing down at the next election has continued to grow, and they look like reinforcing Mr Johnson's critics.

And the House of Lords sent legislation to ban no-deal, and maybe force the PM to seek a Brexit extension, to become law.

He won't break his word. Civil servants are clear he can't break the law. Mr Johnson needs a way to force an election, or salvage his plan to deliver Brexit - maybe without getting an EU deal first. In Downing Street there's no sign they've found one.

The options on No 10's table - after another expected defeat on election timing next week - range from quitting office in hope of getting back in, to counting on the EU to deny the UK the Brexit extension the PM doesn't want.

If there's a cunning plan - and many people, in and out of government, don't believe there is - it seems to need more work. And soon.

SNP Westminster leader Ian Blackford said he was "desperate for an election", but it could not happen until an extension to Article 50 - the process by which the UK is leaving the EU - had been secured.

"It's not just about our own party interests; it's about our collective national interests," he said. "So we are prepared to work with others to make sure we get the timing right."

He said they wanted to make sure the UK did not "crash out" in a no-deal Brexit.

Media playback is unsupported on your device Media caption Emily Thornberry told Today that FTPA election legislation can't be amended

Liz Saville Roberts, Plaid Cymru's Westminster leader, said there was an "opportunity to bring down Boris" and "we should take that".

And a Lib Dem spokeswoman said the group was clear that "we are not going to let Boris Johnson cut and run".

"The Liberal Democrat position for a while now is that we won't vote for a general election until we have an extension agreed with the EU. I think the others are coming round to that," she said.

"As a group we will all vote against or abstain on Monday."

But Housing, Communities and Local Government Secretary Robert Jenrick said the public were "sick of watching politicians bicker" about Brexit and it was time for an election.

He said opposition parties should "stop being cowardly, put the matter to the public, and get resolution at last, so the country can move forward with confidence and optimism for the future".

Media playback is unsupported on your device Media caption So who actually wants an election?

Mr Johnson has promised the UK will leave the EU "do or die" on 31 October, with or without a deal.

But he said on Friday that he would go to Brussels on 17 October and reach a deal.

He added that resigning as prime minister if he did not get one by then was "not a hypothesis" he would be willing to contemplate.

He also said he was "perplexed" by the decision of opposition parties to "run away" from an election.

"All I see is Corbyn and the SNP clubbing together to try and lock us into the EU when it's time to get this thing done," he said.

"It's the most sensational paradox - never in history has the opposition party been given the chance for election and has turned it down."