Pharmaceuticals giant GlaxoSmithKline has said there was nothing abnormal about the recent departures of three of its leading development scientists

The scientists - who were in charge of three of the pharmaceutical giant's six specialist new drug discovery units - resigned from the firm during the last 18 months, a company spokesman told BBC News Online.

It's no surprise that head hunters look at the heads of our research divisions

GlaxoSmithKline spokesman

An earlier report by the Guardian newspaper suggested the scientists' departures would raise "fresh concern among investors about the long term potential of the group".

This was dismissed by the spokesman who pointed out that high calibre people had replaced the departed scientists.

But the Guardian article weighed on Glaxo's shares which slipped 49 pence in early trading to 1,097p, their lowest level in more than five years and about half the stock's value during a peak last summer.

Good reasons

The Guardian article reported the departure from Glaxo of Bob Ruffalo, Marty Rosenberg and Frank Walsh.

The Glaxo spokesman said the first of the three departed scientists left in November 2000 after being offered a good job by a rival drugs group, the spokesman said.

"It's no surprise that head hunters look at the heads of our research divisions," he said.

The second scientist left in May 2001 after reaching retirement age, while the third resigned due to personal reasons, the spokesman said.

"They all left for sound reasons in terms of their careers or personal aspirations," the spokesman said.

The Guardian said Mr Walsh was joining Mr Ruffalo at the US drugs company Wyeth, while Mr Rosenberg had taken retirement.