Silverlink services between London and Birmingham are affected

The company said it has found an engineering solution to the problem with the braking systems on its fleet of Class 321 trains.

The solution has been certificated by Her Majesty's Rail Inspectorate.

The company is now working its way through the fleet of 37 trains affected by the possible problem and two units have been released on Friday morning.

But Silverlink warns that until all the trains have been examined, its service from Birmingham New Street station to London Euston will remain affected.

The possible fault halted all Silverlink services on the route on Thursday, causing disruption for thousands of commuters.

Loose bolts

The company said the problem came to light during a "precautionary examination" and services had been withdrawn on "safety grounds".

An engineer had discovered "loose bolts" which secure the brake disc to the train.

Silverlink will continue to run an alternative bus service until its trains are back on track.

A Health & Safety Executive (HSE) inspector was overseeing further tests on the affected trains.

The fault was found on several of the trains' brakes - we took the entire fleet out Alan Bray Silverlink Trains spokesman

The train model is widely used across the UK and overseas.

Other train companies, including First Great Eastern which uses the same model, said inspectors would also be examining their trains following Silverlink's decision.

First Great Eastern uses the 321 model on its mainline route from London's Liverpool Street to Ipswich and Southend.

Major disruption

They are also used by Arriva Trains Northern on the Leeds to Doncaster route.

Silverlink spokesman Alan Bray said the situation had proved a "major disruption".

More than 300 commuters use each Silverlink service during the rush hour, with about 15 services operating between London Euston and Birmingham New Street.

Passengers have been advised to use alternative forms of transport although other train companies operating the same route will accept some Silverlink tickets.

Mr Bray said Silverlink ticket holders expecting to travel between Birmingham and London - including those travelling from Coventry, Rugby, Northampton, Milton Keynes Central and Watford Junction - could join Virgin, Midland Mainline, South Central, Thameslink and Chiltern services.

Silverlink is part of the National Express Group which is the largest operator of train franchises in the UK.

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