The latest bridge being constructed over the Clyde is running at least six months behind schedule, with almost £5m in European funding for the project in danger of being lost as a result.

Work on the pedestrian crossing spanning the river at Glasgow city centre has largely been on hold since September as a result of the failure of the new quay walls at Tradeston to withstand the pressure of the water.

The full impact of the problems on the timescale and final cost of the £33m project, dubbed the Squiggly Bridge because of its sinuous double-curved shape, are currently the subject of "heated and intense" negotiations between Glasgow City Council and contractors Graham Construction. Both sides are understood to be holding each other liable.

Sources claim discussions "may still take some time to resolve".

But the delay is certain to have an impact upon some, if not all, of the £4.7m in European Regional Development Funding promised to the scheme but only released if the bridge's construction falls within a prescribed timescale.

It will also require some redesigning of the anchors for the bridge on the southern banks although the quay walls on the northern banks at Broomielaw have encountered no such problems.

Edmund Nuttall, the contractors who will carry out the construction work on the bridge, were due to begin last month but are developing the scheme off-site, with the council claiming some of the lost time can be regained.

But the delay could also allow Nuttall to seek penalty payments for not getting on site within the designated timeframe, although the firm's role in the closure of the £26m Clyde Arc, known locally as the Squinty Bridge, for an estimated six months may make that unlikely.

Details of the delay come as repair work on the Squinty Bridge gets under way, over two months since one of its struts collapsed on to its carriageway.

A support cable has been attached to the arm of the Arc to assist in bearing weight as repairs and replacement of the 14 struts take place.

The hold-up is the latest in a string of problems dogging the project. The original proposal, dubbed Neptune's Way and designed by Millennium Dome and Pompidou Centre architect Richard Rogers, was aborted in early 2006 because of spiralling costs and was only brought back on the agenda on the basis that a new scheme would cost half that of its predecessor.

When Graham Construction was awarded the £13m contract for the new quay walls and public realm works there was protraction due to a shortage of sheet piling to shore up the river.

The Herald understands the piling is the source of the problem, with the location of the bridge at an old outflow for surface drainage. The impact of the water flowing into the Clyde has led to a deepening of the riverbed and there have been suggestions the sheet piling may not have been deep enough for the job.

George Roberts, the SNP group's spokesman on transport in the city council, said the party will raise the matter at the authority's land and environment committee today and express concerns on where responsibility lies on the failure of the piling works.

He added: "We will ask who will bear the costs of this and also who will bear any consequential costs including a possible loss of EU funding."

A council spokesman said: "Work on the bridge has been under way off-site since February and we are now looking forward to seeing the build go on-site at the Clyde next month, establishing another highly visible landmark of the regeneration of the Clyde.

"In consultation with the construction team we have been able to reorder the programme of work to ensure that a delay in the wider project does not hinder progress on the bridge itself, which is an important part of the physical enhancement of the riverside between Tradeston and Glasgow's international financial services district."

A spokesman for the Northern Ireland-based contractor said: "Graham Construction has no comment to make on the matter at this time."