GSK said it would have a 68-percent controlling equity interest in the joint venture that will have combined sales of about £9.8 billion ($12.7 billion, 10.9 billion euros).

The deal paves the way for British group GSK to have two UK-listed companies, one specialised in the development of drugs and the other in consumer healthcare.

"Within three years of the closing of the transaction, GSK intends to separate the joint venture via a demerger of its equity interest and a listing of GSK Consumer Healthcare on the UK equity market," a statement said.

"Over this period, GSK will substantially complete the integration and expects to make continued progress in strengthening its Pharmaceuticals business and R&D pipeline."

In a separate statement, US giant Pfizer said the joint venture "will be a category leader in pain relief, respiratory, vitamin and mineral supplements, digestive health, skin health and therapeutic oral health and will be the largest global consumer healthcare business".