LONDON - AstraZeneca may not stay in the vaccine business in the long run and is looking to buy small and mid-sized companies specialising in oncology and cardiovascular treatments, Chief Executive Pascal Soriot said in a Reuters Newsmaker interview on Tuesday.

Production delays, probes by regulators following rare cases of severe side effects and concerns about its relatively short shelf life compared with other shots have stymied adoption of AstraZeneca's COVID-19 vaccine.

Now, in the third year of the pandemic amid a global vaccine supply glut, its use has diminished in much of the developed world as countries have inoculated much of their populations and prefer Pfizer and Moderna's mRNA vaccines as boosters.

AstraZeneca's COVID vaccine has still not attained U.S. approval.

"I cannot be sure the company will remain in the COVID vaccines business," Soriot said in the interview, adding it may also shelve plans to build a broader vaccines portfolio.

AstraZeneca is looking for bolt-on acquisitions, Soriot added.

"We always look for external opportunities," he said.

The CEO has presided over a quadrupling of AstraZeneca's share price in his decade at the helm.

"I can keep doing this job for many years," he said.

The 63-year old was once seen as a natural successor to outgoing Chairman Leif Johansson.

But in July, Soriot quashed speculation he was planning to retire any time soon, saying he expected to work with the company's newly announced chairman-designate Michel Demare for many years to come.

Soriot was tasked with turning around a troubled AstraZeneca - hit by a string of key patent losses and a spate of clinical trial failures - in October 2012, following a stint at pharma peer Roche.

With the Frenchman at the helm, the fortunes of the London-listed Anglo-Swedish drugmaker changed dramatically after he sharpened focus on speciality medicines and the lucrative field of oncology, made acquisitions to refill the company's medicine cabinet, fended off a hostile takeover from U.S. pharma giant Pfizer, and invested heavily in R&D to improve the company's lacklustre drug development success rate.

However, he warned on Tuesday that fewer innovative medicines would be developed going forward due to new U.S. drug price laws.

Asked about inflationary pressures, Soriot said: "We are going to have to become more innovative and productive. We can't expect our selling prices to go up."

(Reporting by Aimee Donnellan and Natalie Grover, Editing by Mark Potter)