The two unions have been in talks over a merger which would create a "super union" for 1.15m workers.

But AEEU general secretary Ken Jackson has criticised his MSF opposite number, Roger Lyons, for making "premature" comments on the merger.

He was responding to Mr Lyons speech at an joint industry conference organised by the two unions, in which he said the MSF executive hoped to make a decision on a merger in December and ballot members next year.

Resignation reports dismissed

Mr Jackson said he had not been consulted on the announcement, and the AEEU executive had not had a chance to discuss the deal.

He said: "We've not yet agreed on all the points, so it is premature to talk of mergers when there are still difficult measures to resolve.

"It will be put to the executive in the new year."

Mr Jackson also dismissed reports that suggested he may retire from the merged union.

He insisted he had no intention of stepping down.

Asked whether the MSF's comments could jeopardise the deal, Mr Jackson said "Yes".

Earlier in the conference, the propsed merger had been welcomed by industry chiefs, including British Aerospace chief executive John Weston.