Trustees of the Thomas Cook pension scheme are plotting an £850m pensions deal with Aviva that will guarantee retirement payments to thousands of former workers at the collapsed tour operator.

Sky News has learnt that Aviva, the FTSE-100 insurer, has been selected as the preferred partner for a deal, although it has not yet formally entered exclusive talks with the trustees.

Thomas Cook's pension schemes are thought to have had roughly 14,000 members at the time of its demise.

The development comes more than three years after Thomas Cook collapsed into liquidation, bringing to an end 178 years of solvent trading.

The travel group's bankruptcy followed months of talks about a rescue deal.

Thomas Cook's brand was subsequently snapped up by Fosun Tourism Group, a Chinese company, which relaunched it as an online travel agent.

Sky News recently revealed that Fosun had decided to put the business up for sale.

Amanda Blanc, Aviva's chief executive, said last week that she was keen to see its bulk annuity pensions division continue to expand.

It recently struck a deal to insure benefits for former employees of Arcadia Group, Sir Philip Green's former high street empire.

Aviva and the Thomas Cook pension trustees both declined to comment.