BANGKOK - Pfizer and Germany's BioNTech denied on Thursday that they were in talks with Thailand's Thonburi Healthcare Group Pcl for a deal to import 20 million doses of the coronavirus vaccine to the Southeast Asian country.

The chief of Thonburi Healthcare Group had said earlier in the day that it would sign a private order for 20 million doses of the Pfizer-BioNTech vaccine, news of which saw the hospitals operator's share price leap over 13%.

"We are not in negotiations with the company," BioNTech said in an e-mail responding to a Reuters query about the deal. It also denied it was in negotiations with any Thai entity.

Company chairman Boon Vanasin had told Reuters a deal would be signed on Thursday with BioNTech, the German firm that jointly developed the mRNA vaccine with Pfizer.

Asked about the companies' denial, Boon later insisted a vaccine deal was still in the works, saying: "We are not doing it directly." He declined to elaborate.

A Pfizer spokesman said the company was only in discussions with Thailand's health ministry and disease control department.

"Neither Pfizer Inc nor any of its affiliates globally, have authorized anyone to import, market, distribute the Pfizer-BioNTech COVID-19 vaccine," he said.

It was not immediately possible to reconcile the conflicting statements by Boon and the two companies.

Thailand is in the early stages of its mass COVID-19 vaccinations programme and is struggling to suppress its most severe wave of infections.

It has relied heavily on the AstraZeneca and Sinovac vaccines but is seeing increased demand for mRNA type vaccines, after concern about efficacy. The majority of the mRNA vaccines ordered will not arrive until the fourth quarter this year.

Boon had said a licensed importer in Thailand would make an announcement on the deal. "I want it to conclude this week or next," he said.

Boon, who has been a vocal critic of the government's vaccine policy, said he had asked for a delivery of 5 million doses this month under the negotiations.

Shares of the hospital group rose as much 13.45% by 0540 GMT, with the benchmark index up 0.62% on earlier reports of the plans.

The state drugmaker, the Government Pharmaceutical Organization, said on Wednesday it had filed a defamation suit against Boon over his criticism of its role in the procurement of Moderna vaccines.

(Reporting by Chayut Setboonsarng, additional reporting by Kay Johnson, Ludwig Burger in Frankfurt; Editing by Martin Petty, Philippa Fletcher and Kim Coghill) ((chayut.setboonsarng@tr.com, Twitter: @ChayutSet; +66854849033;))