The fleet is intended to increase passenger capacity and stem commuter rage over late and cancelled services.

The purchase of up to 30 trains is being finalised with a formal announcement expected before the end of the year, Fairfax newspapers report on Friday.

The revelation comes after the government last May allocated $1.3 billion to the purchase of trains and trams beginning in 2010.

It is believed the 20 per cent growth in rail patronage over the past two years has put pressure on the Government to bring funding forward.

Between 16 and 30 six-carriage sets will be ordered but Treasurer John Brumby has yet to sign off on the final figure.

Thirty-one trains were impounded at the height of the Siemens brake-failure debacle, causing more than 2000 services to be cancelled in January alone. This exposed the lack of spare trains in Melbourne's suburban network as some services ground to a halt.

Connex railway sources say French company Alstom, manufacturer of the X'Trapolis trains, is in line for the contract, following the damaging braking debacle with Siemens.