Mr Sihasak said Hun Sen understood the migrant worker situation in Thailand and initially stressed the Thai and Cambodian governments should cooperate through existing channels such as the memorandum of understanding (MoU) on labour cooperation.
Other discussion topics would include political developments in Thailand and border issues.
The visit follows a recent report the Cambodian prime minister had accused Thai authorities of abusing Cambodian workers' rights during their mass exodus across the border last month, although he said later the Cambodian workers were treated more humanely after complaints from Cambodian authorities.
Foreign Ministry spokesman Sek Wannamethee said the Cambodian workers' exodus stemmed from panic over a groundless rumour that Thai authorities would crack down on them.
Thailand said the authorities had dealt with Cambodian workers based on human rights principles and agreed to investigate any allegations of abuse.
Meanwhile, a centre opened in Samut Sakhon yesterday to register migrant labour as a first step to ending human trafficking in the country.
The centre in Muang district provides a one-stop service for migrant workers from Myanmar, Laos and Cambodia who are staying illegally in the province. It encourages them to register themselves with authorities.
The opening was witnessed by Gen Sirichai Disthakul, the army chief-of-staff in charge of labour issues and human trafficking, permanent secretary for labour Jirasak Sukhonthachat and Myanmar ambassador Tin Win.
Under a plan outlined by the National Council for Peace and Order (NCPO), illegal workers who register at the centre would be given temporary permits to work in Thailand.
Their names would then be sent for verification in 60 days, and the workers who passed the screening process could apply for permanent work permits by using their passports, Mr Jirasak said.
More such one-stop centres would open in 22 coastal provinces in need of migrant workers next Monday, and in other parts of the country by July 15.
Thousands of migrant workers flocked to the centre in Samut Sakhon yesterday to register themselves.
Under the arrangement, each of the migrant workers who registers at the centre will receive a temporary non-Thai identification card. The card carries the migrant's name, age and nationality as well as the name and address of the migrant's employer.
Officials use different colours to distinguish the workers' nationalities. Lao migrants are given blue cards, Cambodians brown cards and Myanmar workers green cards.
An employer will be charged 1,305 baht for the registration of one employee.
A Myanmar illegal worker said she was excited to get her work permit at the one-stop service centre as she had never had one before despite having worked in the country for one and a half years. She said the work permit gave her confidence to work and live in Thailand legally.
Meanwhile, small- and medium-sized business operators cast doubts on the effectiveness of the NCPO's measures to deal with illegal migrant workers.
Nat Chokchaisamut, 52, owner of a small dried-squid processing plant in Samut Sakhon, said only large industries would benefit from the measures as they would find it easier shouldering the cost of passports for alien workers.
Small- and medium-sized seafood-processing factories in the province faced a labour shortage so they needed to employ illegal migrant workers, he said.
For his plant, he said, he had to contact a middleman to provide alien workers to work at a cost of 18,000 baht per head. He said he employed 14 Myanmar workers.
Mr Nat said these workers might stay with him for as long as it took to obtain a passport and work permit. After that, they would leave to work at larger factories, which would force him once again to employ illegal workers. "It's been a never-ending cycle for small business operators like us," he said.
"The military’s orders mean nothing in the long run as the operators will still need a middleman to solve labour shortages,'' he said.
Mr Nat suggested that a law be amended to require migrant workers to work at places where they obtained work permits for a longer period of time, or for them to stay only in provinces where they got the work permits.
Chamras Koy-ari, co-owners of Boonchai Seafood Co, voiced a similar concern. He said authorities should regulate migrant workers to work for at least one year for the employer who helped them obtain work permits. The requirement would help increase the number of registered workers and get rid of undocumented workers.
Samut Sakhon governor Arthit Boonyasophat said his province had 190,000 migrant workers, mostly in the fishing and seafood businesses. Around 100,000 were believed to be working illegally.
Mr Arthit said employers who hired migrant workers who registered at the centre would be given 60 days to arrange passports and work permits.
Suphang Chantawanich, an academic from the Institute of Asian Studies of Chulalongkorn University, told a seminar on migrant workers yesterday the NCPO should eradicate corruption and illegal brokers.
Sompong Srakaew, an official at the Labour Right Promotion Network Foundation, said graft was the main problem leading to large numbers of illegal migrant workers in Thailand. Some employees charged illegal workers 3,000-5,000 baht in a lump sum and another 500 baht per month, or deducted the payment from the migrants' salaries in return for helping protect them from being arrested, he said.