ZURICH (Reuters) - Roche (>> Roche Holding Ltd.) has ruled out major "double-digit billion" purchases but is open to smaller deals, the Swiss drugmaker's chairman said in an interview with a German newspaper published on Thursday.

Christoph Franz said the group was always on the look-out for corporate tie-ups and smaller acquisitions, but ruled out any large-scale deals.

"We are still not planning big purchases. We have a highly innovative research and development pipeline in pharma as well as diagnostics," Franz told German daily Frankfurter Allgemeine Zeitung.

"But of course we don't have the all the best ideas ourselves. That's why we are always looking at the landscape of innovative businesses for cooperation, targeted partnerships and also acquisitions. That is a fundamentally different approach to significant double-digit billion purchases," he said.

This leaves the door open for similar deals to its $8.3 billion (5.04 billion pounds) cash purchase of U.S. biotech company InterMune Inc (>> InterMune Inc) that was announced last month.

In a separate interview on Thursday with a Swiss newspaper, Franz did not rule out making a move for the nearly 40 percent of Japanese drugmaker Chugai Pharmaceutical Co Ltd (>> CHUGAI PHARMACEUTICAL CO., LTD.) that it does not already own.

"In my career I have learnt that it is not sensible to rule certain things out for all eternity," Franz told Basler Zeitung, when asked whether Roche would alter its holdings in Chugai.

There has been talk that Roche may buy the shares in Chugai that it does not already own for about $10 billion, although Chugai has denied it was in talks over a such a deal.

(Reporting by Joshua Franklin; Editing by Mark Potter)