AstraZeneca has suspended its share buyback program, giving new chief executive Pascal Soriot more leeway to devise a strategy to return the British drugmaker to growth.

The company, which has suffered a string of clinical trial failures and patent expiries, said on Monday it was halting the program after buying back shares worth $2.3 billion of its initial target of $4.5 billion.

The company, however, maintained its core earnings target for the full year at between $6 and $6.30 per share.

Soriot, who was previously at rival Roche Holding, started at AstraZeneca on Monday.

"As I assume my new responsibilities at AstraZeneca, I believe this is a prudent step that maintains flexibility while the board and I complete the company's ongoing annual strategy update," he said in a statement.

An AstraZeneca spokeswoman said the board could decide to resume the buybacks or it could identify other opportunities for business investment, such as acquisitions or in its own pipeline.

"It's about maintaining some flexibility from a financial point of view," she said.

Analysts said when Soriot's appointment was announced in August that he could make significant changes, including reviewing the pipeline and doing more deals.