Mr Corbyn was 'empty chaired' at a cross-party summit in parliament this morning after he refused to take part in the SNP-organised event. The Westminster leaders of the Liberal Democrats, Greens and Plaid Cymru all attended.
The pro-EU party leaders agreed to meet on a monthly basis and will invite London mayor Sadiq Khan and Welsh First Minister Carwyn Jones to take part. They will also seek to co-ordinate efforts to amend Brexit legislation at Westminster, and work with campaign groups and trades unions outside parliament in a bid to build support for staying in the single market.
In a joint statement, SNP Westminster leader Ian Blackford, Lib Dem leader Sir Vince Cable, UK Green Party co-leader Caroline Lucas and Plaid Cymru Westminster leader Liz Saville-Roberts said an "extreme Brexit" outside the single market and customs union was "an unprecedented threat to our economy that would destroy hundreds of thousands of jobs".
Targeting Mr Corbyn's calls for a "jobs-first Brexit" outside the single market, the leaders said: "Leaving the single market will cost jobs. Over three million UK jobs are linked to trade with the EU - one in every ten jobs. There is no such thing as a 'jobs-first' Brexit that includes terminating our single market membership – these outcomes are incompatible."
They added: "We are jointly committed to providing that opposition, and call on Labour to join with us - to fail to do so would be an abdication of responsibility, and would make Labour just as culpable for the lasting damage a hard Brexit would do to UK jobs and prosperity.
"Today, we call on the Prime Minister to dismiss any chance of a ‘no deal’ scenario. The possibility must be firmly off the table.
"We will work together in the Commons alongside Members from all political parties to protect the UK economy and prevent any attempts to drag Scotland, England, Wales and Northern Ireland out the single market.
"Moving forward together, we will seek to meet with key stakeholders, such as the TUC and business groups, and the devolved administrations including the London Assembly, to express Parliament’s cross-party desire to avoidthe damage that Brexit will cause, and encourage all efforts to avoid such an outcome."