It looks as though GlaxoSmithKline is on the verge of buying a significant stake in South Africa’s Aspen while rumours persist that the UK-based drugs giant is planning to acquire the USA’s Allergan.

A day after a number of news agencies claimed that GSK is looking to take a minority holding in Aspen, South Africa’s largest generics drugmaker noted that “negotiations were still in progress that may materially affect the price of its securities”. The company added that "shareholders are advised to continue exercising caution when dealing in Aspen's securities until a further announcement is made".

These negotiations are supposedly with GSK and observers believe the latter is looking to buy a stake in the range of 10%-25%. Such a deal would cement the relationship between the two firms which began in July last year when the companies agreed to sell branded generics in emerging markets from 2010.

The rumours about a potential $15 billion bid by GSK for Allergan, which is best-known for Botox (botulinum toxin type A) has been pushing up the latter’s share price in the past few days. However chief executive David Pyott seems to be suggesting that Allergan is looking to make its own acquisitions.

He told Bloomberg that a sale of the company could not be ruled out but noted that “somebody would have to come out with a very compelling proposition”. However Mr Pyott said that “we are constantly looking at new opportunities. We have well over a billion in the bank, and we could do a multibillion-dollar deal if it made sense”.

The areas that Allergan would be seeking to expand include obesity treatment, urology or neurology, as well as aesthetic products and eye care. GSK has regularly stated its desire to diversify its business and one of the attractions of Allergan is that a number of its products do not rely on reimbursement.