Abcam, which makes antibodies, proteins and other products for researchers, announced earlier this month that Horizon had rejected its 270 million pound approach. Abcam said it had announced the news to try to force Horizon to talk.

Abcam said that combining Horizon's capabilities in gene editing with its own products would allow both to extend their reach and influence globally, in the latest attempt at consolidation in the pharmaceutical sector.

Both firms are based in Cambridge, England, a centre for medical research and home to a string of biotech and pharmaceutical companies.

But Abcam said on Wednesday it had decided not to make an offer due to Horizon's rejection and after considering the most recent results of its bid target.

(Reporting by Kate Holton; Editing by Paul Sandle and Edmund Blair)