The head of an Oxfordshire biotech firm's parent company has resigned suddenly.

Dale Pfost, chief executive of US-based Orchid BioSciences, is said to be leaving "to pursue other professional opportunities".

Investors have been concerned about the rate at which Orchid is burning cash.

It made a loss of £8m last year, compared with a £7.4m loss the previous year.

Before joining Orchid in November 1996, Dr Pfost was chief executive of Oxford University spin-off company Oxford GlycoSciences, then based in Abingdon.

Last year, Orchid took over Abingdon-based Cellmark Diagnostics, a pioneer in DNA testing. In April, Orchid announced a 15 per cent cut in its staff, but the Abingdon business escaped the axe because it was profitable.

Now renamed Orchid Cellmark, its 100 staff supply DNA tests for paternity cases and forensic investigations, including work to identify victims of the World Trade Center terrorist attack on September 11 last year.

Orchid has established a search committee to find a replacement for Dr Pfost.

Also leaving immediately is Donald Marvin, who was senior vice-president and general manager of Orchid Diagnostics in the US.

Orchid has been warned by the US stock exchange Nasdaq that it will be removed from the listing unless its share price rises above $1 before January 8. Its share price is now $0.48.

Cellmark Diagnostics, based on work by Sir Alec Jeffrey at Leicester University, was one of the world's first commercial DNA testing laboratories and helped the UK to become a leader in using genetic fingerprinting techniques to help identify criminals, as well as settling paternity cases.