A no-deal Brexit would lead to the loss of “many thousands” of jobs, the business secretary has warned.

Greg Clark urged Tory MPs to “strain every sinew to avoid” crashing out of the EU under the next prime minister, with leadership rivals Boris Johnson and Jeremy Hunt both saying they would be prepared to leave the bloc on 31 October without a deal.

They face a battle to force through their commitments, however, as MPs and peers launch tactical bids to block any attempt to prorogue parliament in order to force through a no-deal Brexit.

Clark told Sky News on Friday that the disruption of a no-deal departure would lead to job losses. “It’s evident that if you have the disruption that comes from a no-deal Brexit there will be people that will lose their jobs. It’s many thousands of jobs. Everyone knows that.”

Asked about claims the UK could weather a no-deal exit on World Trade Organization terms, Clark said: “I think every person that considers the evidence that companies have given – whether it’s in the automotive sector, whether it’s in the food sector, whether it’s in aerospace, in industries up and down the country – you know if you become less efficient and your ability to trade is impeded, then of course losing your competitiveness means there will be jobs lost.”

Clark’s comments came as peers launched a fresh bid on Friday to block any plans by a future Conservative prime minister to suspend or prorogue parliament in order to force through a no-deal exit from the EU.

A cross-party group has laid down amendments to the Northern Ireland bill that seek to build on a similar measure introduced by Dominic Grieve in the Commons on Tuesday.

Lady Hayter, Labour’s deputy leader in the Lords and the shadow Brexit minister, told BBC Radio 4’s Today programme the amendments “would force the government, in September and October, to meet to discuss reports about Northern Ireland, and by doing that parliament would have to be meeting and could not be prorogued”.

She said the amendments stood a high chance of success. “Clearly in the House of Lords we tend to take our responsibility to look after the constitution quite seriously, and a part of this is in making sure that on an enormously important issue like Brexit, parliament is taking the decisions and not just government.”

Q&A What does 'prorogue parliament' mean? Show Prorogation is the official term that marks the end of a parliamentary session. After being advised to do so by the prime minister, the Queen formally prorogues parliament. This takes the form of an announcement in the House of Lords on the Queen’s behalf. It is a speech, written by the government, which usually describes the bills that have been passed during that session and summarises what has been achieved. It means that all work on existing legislation stops, and MPs and Lords stop sitting. Prorogation also automatically kills any bills, early day motions or questions to ministers going through parliament. Parliament can then be reopened a few days later with a fresh slate of legislation intentions, set out in a new Queen’s speech at the formal state opening of parliament.

Dominic Grieve’s amendment passed by only one vote, but Hayter felt that there would be enough support for it in the Lords.

She dismissed the suggestion such a move by unelected Lords was undemocratic. “If the next PM wants to take us out, then all he needs to do is take it to parliament and get their agreement. We’re not saying no to no deal, we’re saying no to no deal without the Commons authorising it.

“I doubt that Boris Johnson would actually go for proroguing parliament frankly,” Hayter added. “But given that is the talk, it seems to me quite right that parliament says at this stage, ‘Hold on, if you’re even thinking of that, don’t do it’, and we therefore take that off the agenda.”