By Charles Haviland BBC News, Colombo

It has been a difficult year in UN-Sri Lankan relations and Mr Holmes is sticking to quiet diplomacy so far

His visit comes after the government stepped up the release of Tamil displaced people held in its camps in the region.

John Holmes’s northern trip has taken him to the places most scarred by conflict and its aftermath: Jaffna, once held by the Tamil Tiger rebels, and the camps near Vavuniya where until recently nearly 300,000 Tamil refugees were held, unable to leave.

Camps 'half emptied'

In recent weeks Sri Lanka’s government has sought to answer its critics. People have been released in their tens of thousands.

The authorities say the camps are now half emptied and that this marks its commitment to have all refugees out by the end of January.

The change has been so rapid that the Tamil National Alliance, a pro-Tiger party, accuses the government of taking people out of the camps and abandoning them without proper infrastructure.

Schools and other facilities in Vavuniya town are now reported to be overcrowded.

Intensive work to remove landmines in the north is continuing.

John Holmes is meeting people recently released and others still in the camps.

This has been a difficult year in UN-Sri Lankan relations and Mr Holmes is sticking to quiet diplomacy so far, with meetings with top officials on his agenda after he returns from the north.