BTG, the technology group privatised in 1992, says it must carry out additional studies before US trials of its revolutionary varicose veins treatment can resume, delaying its launch by two years.
The company, whose shares lost 60 per cent of their value when US regulators halted human trials last month, revealed the gloomy prognosis with its interim results yesterday, saying it might postpone plans to launch the treatment in the smaller European market in 2005.
Ian Harvey, BTG's chief executive, said Varisolve - an injectable foam that destroys varicose veins without surgery - had attracted concern because parts of the foam were found to have entered the bloodstream.
The company will have to carry out animal tests and other laboratory work to reassure the US Food and Drug Administration that these discoveries do not mean the treatment is unsafe. Human trials will not now be completed until 2007, implying a US launch a year later.
Mr Harvey said he was seeking to meet European regulators to see if they shared the FDA's concerns. The future of the more advanced European trial programme would be examined at that meeting and the company would then consider how or whether it should manufacture the product in Europe before a launch in the more profitable US market.