DRUGS company Pfizer has approached AstraZeneca over plans to carry out a multi-billion pound takeover.
Pfizer, which made an initial approach in January, says market developments have prompted bosses to return with another approach.
The company said it was considering its options on the move.
Experts say AstraZeneca, which has plants in London, Cheshire and Bristol, would cost Pfizer about £65bn.
If the deal went through, it would mark the largest takeover of a UK firm by a foreign company.
Buying AstraZeneca would give Pfizer, which makes Viagra, access to a number of cancer and diabetes drugs.
Pfizer said its initial offer in January was a combination of cash and shares worth £46.61 per AstraZeneca share, worth £58.8bn in total.
Ian Read, Pfizer, chief executive, said: “We have great respect for AstraZeneca and its proud heritage.”