A UN peacekeeping committee reportedly barred Major General Shavendra Silva of the Sri Lankan Army from attending their meetings.
"Following careful consideration and consultation with other special advisory group members, the chair, Louise Frechette, has advised Major General Shavendra Silva of Sri Lanka, that his participation is not appropriate or helpful for the purposes of this group," said a statement released by Frechette.
"He will not participate in its deliberations," added Frechette, a former UN deputy secretary general and top Canadian diplomat who was named by Ban to chair the committee.
But Silva still attended the first meeting of the advisory panel to UN leader Ban Ki-moon, where he sat in the room but did not speak. No other member spoke to him and no documents were given to him, diplomats were quoted as saying.
"If Frechette had not acted this panel would just have fallen apart, nobody wanted him on the panel," reports quoted one diplomat as saying on condition of anonymity.
The nomination of Silva, Sri Lanka's deputy UN ambassador, to the panel by Asia-Pacific countries at the UN set off a storm of protest by rights groups.
Silva is accused of war crimes committed in the final days of the Sri Lankan war in 2009.
See our earlier posts:
Pressure piles on Ban over Silva appointment (19 February 2012)
Navi Pillay raises concerns over General Silva at UN (14 Feb 2012)
Alleged war criminal appointed to UN Peace Keeping group (27 January 2012)