The government has been urged to issue travel warnings for Cambodia and Myanmar over fears Hongkongers could be trafficked there in job scams.

Authorities say five Hong Kong residents believed to be in Southeast Asia are currently unaccounted for.

Immigration officials say they have had 17 trafficking reports involving the region so far this year, with a number of suspected victims eventually managing to leave safely from Myanmar, Cambodia, Thailand and Laos.

DAB legislator Elizabeth Quat said on an RTHK programme on Thursday that the government should consider issuing travel warnings for Cambodia and Myanmar to alert people to the dangers of job scams there.

"It's rare to issue travel warnings because of this sort of situation, but the situation keeps changing," she said.

"I think the Security Bureau can consider issuing travel warnings and even if it can't, officials need to step up publicity online and in different media to advise people to stay alert."

On Commercial Radio, former Yau Tsim Mong district councillor Andy Yu said he is working with the families of two Hong Kong men who are thought to be being held captive in Myanmar.

He said the pair went to the country in June and are believed to have been forced into taking part in fraudulent activities. He said it's thought their captors won't allow them to leave until they swindle money from a certain amount of people.

The police should investigate whether there are human trafficking syndicates in Hong Kong, Yu said.

"A visa is required to visit Cambodia and Myanmar. Is this a trace that the police can follow?" he asked.

"I believe the syndicates would have some representatives in Taiwan, Macau and Hong Kong who can speak local languages in order to lure people overseas... I think the Security Bureau and the police can assist on that front."

Meanwhile, the Foreign Ministry's office in the SAR said it attaches great importance to the safety of Hongkongers overseas and is working with local embassies and consulates to find the missing people.