MANILA (Reuters) – At least 11 people have been killed and more than 300 treated in hospital after drinking coconut wine in the Philippines, including some who were celebrating at a Christmas party, health and local authorities said on Monday.

The poisoning occurred in Laguna and Quezon, two provinces south of Manila, and all had consumed lambanog, a drink popular in provinces and consumed widely during holidays and celebrations.

Many were admitted to hospitals on the urging of mayor Vener Munoz in Rizal, Laguna, where the deaths occurred between Thursday and Sunday.

Two people who had been in critical condition were improving, he told local radio. The coconut wine that was consumed had been made in his town, he added.

Blood tests and samples of leftover lambanog would be collected and analyzed on Monday, the Department of Health said.

“All had a sad history of lambanog ingestion,” the department said, referring to those poisoned.

“Some bought for leisure drinking and birthday party, while others were donated by local officials during their Christmas party.”

Unregulated production and sales of lambanog are common in the Philippines, and it is often made illegally with dangerous additives.

The country’s Food and Drug Administration (FDA) has previously warned about the dangerous and prohibited use of methanol as an additive in home brews.

A year ago, the FDA and police were deployed to locate and confiscate unregistered lambanog that was being openly sold to the public, and threatened to prosecute sellers.

Twenty-one people died after consuming lambanog last year, media reported.

(Reporting by Martin Petty and Neil Jerome Morales; Editing by Stephen Coates)