Hong Kong Chief Executive Carrie Lam Cheng Yuet-ngor has written a letter to Philippine President Rodrigo Duterte over the case of four Hong Kong people jailed for life in the Philippines on drugs charges.

Her office said Lam wrote to convey her and society’s “deep concerns” over the case after considering relevant information and requests by the men’s families, Apple Daily reported. However, no details of the letter were disclosed.

A spokeswoman from her office said the Security Bureau and Immigration Department will continue communicating with the Liaison Office and the Chinese Embassy in the Philippines to provide assistance.

The four Hong Kong men aged between 31 and 51 were convicted of possessing 467.8 grams of methamphetamine, which was found in one of the men’s backpack on a fishing boat near Subic during a raid in 2016.

The four men claimed innocence, saying police found nothing during an initial search. A Philippine court sentenced the four to life in prison on December 14 last year. Their lawyer filed a writ to the court in a bid to overturn the conviction.

Legislative councilor James To Kun-sun, who has been helping the four families, said a direct letter from the head of the government is still a significant development.

A crowd-funding initiative was launched in Hong Kong to help the four families. They had collected about HK$400,000 (US$51,086) so far, although their target was HK$3 million for the legal expenses relating to the appeal.