The contract research organisation (CRO) said this move was to meet growing demand for its drug development services.

As part of the expansion, it expects to invest up to £15m (€22m) to build a new 34,000-square-foot facility in Bellshill, Lanarkshire where the company has employed more than 350 people since February.

The investment - partly supported by a regional grant of £4.5m - will also include the creation of 390 new positions in biostatistics, data management, pharmacovigilance, product development, and clinical trial management and monitoring, the company said.

The firm received a £3m similar grant two years ago after a previous expansion, which resulted in 100 new jobs.

"With the biopharmaceutical industry increasingly relying on global outsourcing to speed drug development and reduce costs, demand for our services continues to grow," said Fred Eshelman, chief executive officer of PPD.

"Scotland offers both intellectual and technical resources that make it an important hub for our global clinical research operations."

PPD's announcement comes two weeks after the company posted healthy financial results for the second quarter of this year boosted by its development services business. The CRO's operating income was $61.1m (€44.2m), an increase of 24.6 per cent compared to $49.0m for the same period last year.

In addition, the firm recorded sales of $350.0m for the period, 13 per cent higher than last year's revenues.

The company's development segment once again was the strongest performer, with a 13.5 per cent increase in sales to $316.5m and an operating profit up 30 per cent to $64.7m on the same period in 2006.