Politicians must show courage when it comes to backing major public building projects, according to the man behind the Edinburgh trams project.

The flagship scheme has been hit by a dispute with one of the main contractors, Bilfinger Berger, resulting in delays to the work.

The row has prompted criticism from MSPs in the city, but Richard Jeffrey, chief executive of Tie, the firm set up to oversee the scheme, voiced concern that it may prevent future infrastructure schemes getting the go-ahead.

"We've got to be very careful that we don't make these project politically untouchable," Mr Jeffrey said in a radio interview on Monday.

"It's always easier for people to oppose things than to propose things.

"Proposing and supporting these major long-term infrastructure projects does take political courage.

"I think we've got to be very careful that we don't end up in a situation where our politicians are frightened to make these long- term infrastructure investment decisions because they're worried about what others are going to say.

"This mentality of opposing things might be politically expedient, but actually it leaves us as a society with a decaying infrastructure and no investment for the future."

It emerged last month that the trams project is facing cost overruns of more than £50m.

Contingency plans were drawn up to borrow the additional funds for the project, which had been expected to cost £545m.

The Scottish Government had opposed the scheme, but lost a vote in Parliament on the issue as opposition parties joined forces to back the project.

IN DETAIL

• Tram bosses deny online rumours project will be scrapped
• Soaring costs could see Edinburgh tram line stop short
• Edinburgh tram project faces further delays