A high-level delegation from the United Nations High Commission for Refugees was expected to arrive in Malaysia on Wednesday to seek talks with the government over its treatment of Acehnese asylum seekers.
By Jonathan Kent
BBC correspondent in Kuala Lumpur
The agency has protested at Malaysian plans to return refugees to the troubled Indonesian province of Aceh, where it says their lives could be at risk.
The military operation in Aceh has created hundreds of refugees
The team flying in from Geneva includes the head of the UNCHR's Asia Pacific bureau and its director of international protection.
It is a measure of just how seriously the United Nations refugee agency takes Malaysia's plans to deport hundreds of Acehnese asylum seekers.
Most were arrested as they tried to register as refugees with the UNHCR in Kuala Lumpur last month.
Migrants or refugees
The High Commissioner himself, Ruud Lubbers, rang the Malaysian Foreign Ministry last week to ask for a moratorium on the deportations.
However, Malaysian law doesn't recognise the status of refugees and the country isn't a signatory to any of the international conventions that protect them.
Rather it sees itself as a magnet for illegal migrants in South East Asia, attracted by the country's prosperity and stability.
But UNHCR officials say Malaysia is subject to international law which says states cannot expel people to places where they may be in danger.
Risk of return
Both the UNHCR and the asylum seekers themselves say that anyone returned to Aceh under current circumstances would be at serious risk.
Since May hundreds of people have been killed in fighting between the Indonesian military and Acehnese separatists.
No meeting between the visiting UNHCR officials and the Malaysian government has yet been finalised but the team hopes to meet with a senior minister before it leaves on Saturday.