Employees at German flag-carrier Lufthansa and American Airlines, the second biggest carrier in the US, are both in discussions over possible strike action.

In Germany, Vereinigung Cockpit, the pilots’ trade union, has announced plans for industrial action next week. Pilots are expected to walk out for four days from Monday, in what could be among the most severe strikes in recent German.

Pilots are worried about possible job cuts following a sharp downturn in passenger numbers. Recent acquisitions by Lufthansa – including Austrian Airlines and British Midland – could also see German jobs transferred overseas, according to pilots.

Vereinigung Cockpit official Ilona Ritter explained the strike was a last resort after months of negotiations with the airlines, explaining: “Lufthansa could end this very quickly if they come to us.”

The strike – which would also see pilots at Lufthansa Cargo and Germanwings, its low-cost carrier walk out – was supported by over 90 per cent of those who had taken part in a ballot.

As many as 4,000 pilots could walk out.

Across the Atlantic, American Airways is facing possible disruption as unions prepare to ballot ground staff over possible industrial action.

The Transport Workers Union (TWU) – which represents staff at the airline - confirmed it will ask federal mediators to allow employees to walk away from contract talks with American if there is no deal by March 8th.

However, both Congress and president Barack Obama can block strike action at the airline.

The union represents up to 28,000 workers at American Airlines and American Eagle, including mechanics and bag handlers. Negotiations have been ongoing for four years in some cases, argue union reps, with staff concerned over pay and conditions.

American Airlines parent company - AMR - has lost a total of $3.6 billion (£3 billion) in the last two years. This has been due in part to rising fuel prices (which have now largely eased), as well as a slump in travel because of the recession and tough competition from low-cost carriers.

President Bill Clinton ordered American Airline’s pilots back to work, just minutes after walking out on strike in 1997.