Three of Britain's biggest trade union chiefs and the boss of British Airways have resumed talks aimed at resolving their dispute.

Union representatives met with BA negotiators under the guidance of conciliation service Acas.

They are seeking to find common ground on the swipe cards dispute which has threatened the future of the airline.

BA has moved from a system of paperwork clocking in to an electronic system.

Airline ground staff, some of whom earn just £10,000 a year, have warned that the new system could worsen working conditions.

Differences between the unions are said to have held back initial talks with BA.

The unions had initially failed to agree on a unified position - with the GMB holding out in total opposition to the swipe card system.

But a series of bilateral talks between BA chief executive Rod Eddington and each of the major unions representing check-in staff has led to hopes that the issue will be settled without further strike action.

TGWU boss Sir Bill Morris struck a conciliatory note ahead of Tuesday's meeting.

"We stand ready to enter into joint and collective negotiations with the company," he said."The exploratory talks with Rod Eddington were cordial but frank. Last week we established a framework for agreement which is still in place. We are very concerned to restore the confidence of passengers and of our members."

Amicus assistant general secretary Paul Talbot praised a "worthy exchange" of words.

"They were very sensible and constructive discussions," Eddington added.

The GMB's Kevin Curran accepted that the talks were held in a "very positive environment".

TUC chief Brendan Barber was brought in to resolve the intra-union differences as the dispute threatened to send the airline millions of pounds into debt.

He sought to bring the unions together as talks got under way.

A TUC spokesman said the general secretary would try to "work out a common position and use that as a basis to approach management".