New Midland Metro lines are still on course despite the Government binning a £500 million tram line in Liverpool this week, according to West Midland transport officials.

The Merseytram decision - which has prompted bitter recriminations and a possible legal challenge by Liverpool's transport leaders - came the day after it was revealed the cost of two extensions to the West Midlands tram network had spiralled by 74 per cent.

The Department for Transport recently appears to have gone cold on light-rail schemes in Leeds and Manchester, among others.

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Passenger transport executive Centro maintained the Liverpool situation was " considerably different" from that in the West Midlands.

But last night a Birmingham Labour MP said the Midland Metro network was even less cost efficient than Merseytram and called for it to be scrapped, too.

Perry Barr MP Khalid Mahmood, who has previously voiced opposition to plans for a future tram route along the A34 in his constituency, said: "They made the right decision for Liverpool and now I want them to make the same decision here."

The MP, who was parliamentary private secretary for former Transport Minister Tony McNulty, added: "Alistair Darling should follow the example of the Merseytram, because that project was actually more costefficient than what we have in Birmingham. "If he has cut that, he should certainly do the same here. The Midland scheme is not viable and never has been and it worries me that some of the costs may be met by cutting spending on essential services councils provide." One positive sign for the West Midlands is the Government's clear desire to run a road pricing pilot in the region.

Transport insiders believe it would be hard for the Government to turn down a high-profile tram system when congestion charging depends upon good public transport alternatives for drivers.

This week Centro admitted the estimated cost of two extensions - through central Birmingham and between Wednesbury and Brierley Hill - had risen from £ 212 million in 2002 to £369 million when construction is due to start between 2008 and 2011.

Centro put the higher bill down to inflation and a number of "tweaks" they have had to make to the schemes following planning inquiries.

A Centro spokesman said: "We have not yet submitted a final business case to the Department for Transport, so it is not possible to make any such direct comparison (with Liverpool).

"However, all the indications are that the currently approved extensions to the Midland Metro will show an excellent business case with a return on investment well above Government criteria.

"We will also have the assurances in place regarding local contributions, with the lion's share coming from

developer contributions."

One of the major stumbling blocks to the Government agreeing to release £170 million to the Merseytram project was a lack of local authority agreement in Merseyside.

However, the Centro spokesman added that expanding Midland Metro was "central to the Local Transport Plan agreed by all West Midlands city and borough councils".