The union representing hundreds of workers at BAE Systems shipyards in Glasgow said yesterday it supports the company's plan to build six naval tankers in South Korea, but only if Clydeside yards are too busy constructing two Royal Navy aircraft carriers.

Unite said BAE yards at Govan and Scotstoun will not have the capacity to build both the tanker fleet and the aircraft carriers - a position taken by the company.

BAE has formed a joint venture with Southampton-based VT, formerly Vosper Thorneycroft, to do the initial work on the carriers. The final assembly will be completed by Babcock at its dockyard in Rosyth.

Contracts for the carrier programme are expected to be signed next month.

In principle, Unite does not like to see work going overseas but has made an exception for the tanker contract.

"If we can't do the carrier work, then someone has to do it," Duncan McPhee, Unite convenor at the Scotstoun yard, told The Herald. "We (Britain) really need the ships."

He was referring to plans by BAE and its two partners to build the tankers for the Royal Fleet Auxiliary in South Korean yards if the consortium wins the bid for the ships.

BAE will join forces with British firm BMT Defence Services and South-Korean-based Daewoo Shipbuilding & Marine Engineering to bid for the contract for the ships, the first part of the Military Afloat Reach and Sustainability programme.

Normally, contracts for naval vessels are only handed out to British companies but the government has decided to allow foreign firms to bid for the tanker deal.

The timeframe for completing the first of the six auxiliary ships is tight - the first is scheduled to enter service in 2012.

McPhee said he hoped that one or more of the ships could be built on the Clyde "if there is a gap in work on the carriers". BAE also holds this view.