The migrants, mainly from North Korea and Pakistan, are using Bangkok as a transit point to resettle in a third country.
The city is a good channel for them as it houses the Asia-Pacific office of the United Nations High Commissioner for Refugees (UNHCR) where they can ask for refugee status, according to immigration police.
They are also given help by human rights advocates and even foreign diplomats.
“If we don’t arrest them, more illegal migrants will come to Thailand. This will lead to more crimes and human trafficking,” said Phongnakhon Nakhonsantiphap, deputy chief of investigation at the Immigration Bureau.
North Koreans who illegally enter northern Thailand from Laos are reportedly helped by human trafficking gangs to initially travel to China, from where they travel in cargo boats to Laos, according to investigations by the bureau and the Internal Security Operations Command.
Once in Thailand, officials from the South Korean embassy will contact them and facilitate the last leg of travel to South Korea, which is their final destination.
However, because their entry and stay in Thailand are both illegal, the North Korean immigrants must be prosecuted in court, according to the Immigration Bureau.
While the North Koreans claim hardship in their country as the reason for resettlement in South Korea, illegal Pakistani migrants, mainly from a minority Islamic sect, cite religious conflict as the main cause for them trying to get to Europe and America.
The Ahmadiyya, the name given to people belonging to the sect, want the UNHCR to grant them refugee status.
In some Islamic countries, they claim, the Ahmadiyya are killed as they are not accepted by mainstream Muslims.
Despite their plight, Pol Lt Col Phongnakhon said, if they are illegal migrants in Thailand, they have to be tried, fined and held at the Immigration Bureau.
On Dec 14 last year, immigration police arrested 96 Pakistani Ahmadiyya at a housing estate in Pathum Thani. All have since been prosecuted under Thai law.
However, they were later released on bail on human rights grounds, Pol Lt Col Phongnakhon said.
Last Monday, the group was helped by human rights advocates from the Thai Committee for Refugees Foundation.
The Immigration Bureau requires them to report to police every 30 days while waiting for the UNHCR’s response to their request.
In the meantime, the foundation has agreed to provide them with accommodation and occupational training.
Also, the bureau has adhered to the non-refoulement policy, a principle under international law not to send refugees to places where their lives and freedom will be threatened. They ask the illegal migrants where they want to go before being deported.
All insist they will not go back to Pakistan, Pol Lt Col Phongnakhon said.
According to an investigation, most of the 96 Ahmadiyya are well-to-do and entered Thailand legally. However, they were categorised as illegal migrants because they had overstayed their visas. The over-stay was caused by their wait for refugee status.
“Investigators have found they are not involved in criminal or terrorism activities,” Pol Lt Col Phongnakhon said.
But their appearance in large numbers has worried other residents in the housing estate, he said.
The Immigration Bureau has urged members of the public to call 1178 if they have information about illegal immigrants in their neighbourhood.
Operators of home or car rental services were also warned against helping the immigrants. People who provide accommodation for illegal immigrants could face up to 10 years in jail or a fine of 100,000 baht, while those providing them with transport risk five years in prison or a fine of up to 50,000 baht, he said.