Hitachi says it remains committed to building the new plant in Newton Aycliffe, despite delays in the final sign-off.
The Japanese company is planning to build a £4.5bn train factory at Aycliffe Industrial Park, creating hundreds of jobs and pumping millions of pounds into the local economy.
And it has moved to reassure the region again, after it emerged the final closure of a deal to build a new fleet of intercity trains has been delayed until May.
The Intercity Express Programme (IEP) contract with the Department for Transport (DfT) was expected to have been fully signed by the end of last year.
But in its latest update on its business plan, the DfT said delays to securing planning permission and the need to conclude commercial discussions with the Agility Trains consortium – of which Hitachi is the main shareholder – and their banks had resulted in a delay to commercial close to May this year.
The then Transport Secretary Philip Hammond announced the scheme’s go-ahead last March.
A Hitachi spokesperson said: “Since then, preferred bidder Agility Trains and its main shareholder Hitachi have worked together with the DfT on the IEP.
“After planning permission for three depots along the Great Western Main Line was granted in early February 2012, we now envisage to come to a close of contract in the second quarter of 2012.”
She added: “Although the programme is very complex, this slight delay will not impact the latest delivery timescales and Hitachi expects to go ahead with the construction of the rolling stock manufacturing and assembly plant in Newton Aycliffe once the IEP contract has been signed.
“We are highly committed to IEP and to the North East as the new home to our plant and are looking forward to becoming a member of the business community in County Durham. “
Sedgefield MP Phil Wilson said the scheme had only been held up by the process of securing planning permission for the depots, rather than any problems with Hitachi or the DfT.
“They anticipate starting to build the factory at the back end of this year or the beginning of next year,” he said.
The Labour MP added it was “great news” because Hitachi would bid for other major contracts, such as a new high-speed train fleet.
“Considering they built the bullet train in Japan, they know a thing or two about high speed rail,” said Mr Wilson.
A DfT spokesman said there had been a “short” delay to ensure commercial contracts were right. But he said passengers on the Great Western and East Coast routes were on course to benefit from “massive” improvements thanks to the new fleet of intercity trains.