A Japanese firm announced the closure of a North-East electronics factory, with the loss of hundreds of jobs, last night, after the cut was leaked in a confidential memo to the Government.

Officials of Sumitomo Electric Wiring Systems were said to be angry at the disclosure, in a telegram to the Foreign Office earlier this month, by Sir Stephen Gomersall, the British ambassador in Tokyo.

The company said it would close its site at Sunderland, in the first half of next year, with the loss of more than 400 jobs. It is expected that about 100 workers will move to another site.

The firm, which opened the Sunderland plant six years ago, said it had intended to announce the closure in August, after consultation with unions.

"It is with regret that the company has not been able to utilise the usual channels of communication. This is the result of Press comments following the leak of a Government document," a spokesman said.

Sumitomo was mentioned in Sir Stephen's memo, warning of the threat to jobs if the UK stayed outside the euro, as preparing to cut 550 jobs in the Midlands and North-East.

Sir Ken Jackson, general secretary of the Amalgamated Engineering and Electrical Union said: "This is a shocking decision that will have a terrible impact on an area of already high unemployment. We urge the company to look at alternatives. It cannot just walk away from its responsibilities."

Sumitomo, a major supplier to nearby Nissan and other Japanese car firms Toyota and Honda, said the strength of the pound against the euro was a factor in its decision.

It is to transfer production to plants in Poland and Slovakia.

The announcement follows last week's warning by Nissan president Carlos Ghosn that it was struggling because of the strength of the pound.

Sumitomo spokesman David Breese said: "I think the problems we have experienced are an industry trend, which was highlighted by Mr Ghosn last week. There are, increasingly, pressures in the car industry and the strength of the pound and the euro was certainly a factor in the decision."

The Department of Trade and Industry said it would work to try to minimise job losses and help redundant employees find new work.

John Edmonds, general secretary of the GMB union, said: "Sumitomo is merely the latest name on the roll call of companies that have fallen as a result of the high value of the pound.

''The Government must start to make clear that the current level of sterling is simply no longer sustainable."

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