Thomas Cook has issued a warning to its shareholders

Thomas Cook warned its shareholders this weekend that their failure to back two planned disposals could lead to the firm going into administration.

The tour operator has posted documents to shareholders in which it explains the financial importance of the planned sale and leaseback of part of its aircraft fleet and the disposal of five Spanish hotels.

Thomas Cook said in the circular that its directors were confident that shareholders will deliver the required majority when they vote on the disposals at a general meeting in London on May 29.

Failure to support the fundraising move would jeopardise the company's recent £1.4 billion deal with lenders, including Royal Bank of Scotland and Barclays, to extend the maturity of its bank loans to 2015.

That agreement has been hailed as a key step in strengthening confidence in the holidays firm, which blamed a "number of exceptional external shocks" since 2010 for its poor trading.

In this weekend's circular it confirmed losses of £262.7 million for the winter and said the particularly poor performance of its North American and French businesses contributed to the bigger half-year loss.

Bookings for the second half have been more encouraging but Thomas Cook said much will now depend on how it performs in the important "lates" market.

The company was plunged into crisis in November after it went back to its lenders to ask for an additional £100 million lifeline, sparking fears of a collapse, but it is now hopeful that it has a platform for recovery.

Its turnaround plan for the UK business includes focusing on fewer and better-quality hotels and a drive for more online bookings.

A spokesman for Thomas Cook said: "We fully expect the hotel sale and sale and leaseback to go ahead as planned."