British pharmaceutical giant GlaxoSmithKline said yesterday that it has agreed to buy US-based skincare group Stiefel Laboratories in a deal worth up to $3.6 billion.

The deal for Stiefel, a maker of anti-itching creams, acne treatments and other skincare products, had been widely expected after US media reports over the weekend.

"GSK and Stiefel Laboratories today announced that they have signed an agreement to create a new world-leading specialist dermatology business," the pair said in a joint statement.

"Under the terms of the agreement GSK will acquire the total share capital of Stiefel for a cash consideration of $2.9 billion.

"GSK also expects to assume $0.4 billion of net debt upon closing. A potential further $0.3 billion cash payment is contingent on future performance."

Stiefel is part-owned by US buyout firm Blackstone Group and was put up for sale earlier this year.

"This transaction will create a new world-leading, specialist dermatology business and re-energise our existing dermatology products," said GSK chief executive officer Andrew Witty in the statement.

"The addition of Stiefel's broad portfolio will provide immediate new revenue flows to GSK with significant opportunities to enhance growth through leveraging our existing global commercial infrastructure and manufacturing capability." Mr Witty said the acquisition was part of GSK's strategy to grow and diversify its business.

In midday London trade, GlaxoSmithKline shares were up 0.77 per cent while the overall market was down 1.3 per cent.

Analysts were generally positive on the deal with Jonathan Jackson, head of equities at Killik & Co., saying it "represents a further step in the group's previously-announced strategy to grow and diversify its business.

"It provides immediate new revenue and synergy opportunities," Mr Jackson said, adding that his house was a buyer of the stock which has fallen 19 per cent so far this year.