Pharmaceutical company Novartis has increased its share in a biopharmaceutical firm that specialises in gene therapies.

Novartis, which has a manufacturing base in Liverpool, exercised its right to buy 213,888 unregistered shares of Alnylam Pharmaceuticals for $5.4 million (£2.7 million), bringing the company's stake up to 13.4 per cent.

In 2005, Novartis bought 5.3 million shares of the company for $58.8 million.

Researchers at Alnylam are working on ways to turn off bad genes that cause diseases in the body.

Miller Tabak, analyst Les Funtleyder, told Forbes: "Novartis is putting down a bet on a technology platform that may have future applications."

He said bigger biomedical firms want to do these kinds of deals "because if it turns that these technologies have some kind of promise you don't want to be left behind".

According to Datamonitor, Novartis completed more deals than any other pharmaceutical in 2005-06.

As well as Novartis, the northwest is also home to 230 pharmaceuticals including Bristol-Myers Squibb, Sanofi-Aventis, Renovo, Eli Lilly and Astra Zeneca.