By Bill Hayton
BBC News, Hanoi
A US-based rights group has accused Vietnam of maltreating homeless children to improve the appearance of the capital, Hanoi, for visitors.
The summit will attract 20 regional heads of government
Human Rights Watch says it is particularly concerned that street children are vulnerable to arrest this week as the city hosts a key summit.
Their number has visibly reduced in the run-up to the Asia-Pacific Economic Cooperation meeting.
Twenty heads of regional governments are scheduled to attend.
Walking around Hoan Kiem lake in the centre of Hanoi usually involves being encouraged to buy postcards, books or souvenirs by a few young people - but not at the moment.
The number of such street workers has dropped in the past few weeks and one security official on duty near the lake told the BBC his instructions were to detain any street children he encountered.
The official said: "The problem with the street children shining shoes and selling books is that they normally follow foreigners and tourists.
"We will put them in the social protection centre so they will be taken care of by the state."
But the centre, a short distance outside Hanoi in a place called Dong Dau, has a reputation for brutality.
Former inmates interviewed by Human Rights Watch said they were routinely beaten with truncheons, locked in cells with at least 10 other people for 23 hours a day and denied medical treatment.
The Vietnamese government has so far not responded to requests to comment on the report.
Human Rights Watch says the abuses it has documented are against both international and Vietnamese law.
It has called for an independent audit of the centre and a plan to improve conditions there.