Novartis Chief Executive Joe Jimenez played down talk that it was looking to sell its one-third voting stake in crosstown rival Roche, and certainly not at its current market price.

There has been widespread speculation that the Novartis could be heading for a change of strategic direction - including a possible sale of the Roche stake - following the appointment of a new chairman on Wednesday.

"It's a strategic purchase," Jimenez said of the holding during an interview at the World Economic Forum in Davos.

"What we mean by that is the value of that stake is worth more than the market price today. Today, you couldn't recreate a 30% stake in a company like Roche by purchasing on the open market.

"From a shareholder standpoint, we wouldn't want to sub-optimise the asset, just like we wouldn't want to sub-optimise any other asset."

Previous Novartis boss Daniel Vasella secured the 33% voting stake in Roche between 2001 and 2003. Vasella initially said he wanted to merge the two Swiss drugmakers but, after hitting resistance, kept the block as a long-term investment.

Vasella struck at a low point for Roche, whose stock has since risen sharply, driven by its leading position in cancer medicines.

The rise in Roche's valuation has put the group out of reach of Novartis as a takeover target but the holding has proved to have been a rewarding investment, with the voting bearer shares held by Novartis currently worth some $12 billion.

Investors have suggested several times that Novartis might cash in its investment, although Vasella's presence as chairman was seen as a potential obstacle. Vasella's replacement by Joerg Reinhardt, who worked for nearly three decade at Novartis before moving to Bayer in 2010, has now rekindled the idea.

Analysts believe one way to unwind the holding would be for Roche to pay a significant premium for the Novartis stake as part of a share repurchase programme, though there are no indications that this is on the agenda.

Investors have also pondered whether Novartis should sell its vaccines business or some other units to make the company more focused. Jimenez, however, said all the company's operations had good growth potential.

"We believe that with our commitment to R&D we can drive growth in all of our divisions, so at this time we are not anticipating a change in the structure of the company, but at the same time we are constantly evaluating," he said.