Bosco Ntaganda has been indicted for allegedly recruiting child soldiers
An indicted war criminal is playing a leading role in the UN mission in the Democratic Republic of Congo, according to documents seen by the BBC.
A Congolese army paper suggests ex-rebel leader Gen Bosco Ntaganda has a major part in the command chain, says a BBC correspondent in the country.
The UN-Congolese force is fighting Hutu rebels in the eastern DR Congo.
The force says Congolese authorities have given assurances that Gen Ntaganda is not involved in joint operations.
Gen Ntaganda - known as "the Terminator" - is wanted by the International Criminal Court for alleged forced enrolment of child soldiers in 2002-2003.
The BBC's Thomas Fessy in the capital, Kinshasa, has seen an internal Congolese army document, dated 4 April 2009, which refers to Gen Ntaganda as the deputy co-ordinator for the joint mission's operations.
Our correspondent says the paper - which notes that Gen Ntaganda spoke during an operations meeting - proves he is playing a major role in the chain of command.
A high-ranking Congolese army official confirmed the former rebel leader was involved in the operations, describing him as an adviser to the operations commander.
The UN's peacekeeping force in DR Congo, which is known as Monuc, denied the report.
"Monuc has been in very close touch with the Congolese authorities working with the Congolese military," spokesman Kevin Kennedy told the BBC's Network Africa programme.
"A document has been shared with Monuc concerning the command for the operations that Monuc is working on with the FADRC (Congolese national army).
"Bosco Ntaganda's name does not appear on that document, so we have from our Congolese counterparts an assurance that he is not part of the command."
'Head in the sand'
Earlier this year, when the Congolese government said he could be useful in bringing peace to the eastern DR Congo, Monuc said it would not participate in any operation involving an indicted war criminal.
WHO IS BOSCO NTAGANDA?
Known as "the Terminator"
Indicted for war crimes; conscripting children to fight
Ex-ally of rebel chief Thomas Lubanga, detained at The Hague
Ntaganda refused offer of a Congolese army post in 2004
He joined Gen Nkunda's CNDP two years later
Split and joined Congolese army in January 2009
New York-based Human Rights Watch accused Monuc on Wednesday of deliberately ignoring the issue.
"We are very worried by this information and it seems to us that the United Nations is acting like an ostrich with its head in the sand," Anneke Van Woudenberg, the group's senior researcher on DR Congo, told the BBC.
"It's time now this is addressed head on. Rather than denying or ignoring the role being played by Bosco Ntaganda, the UN should be actively seeking his arrest and transferring him to The Hague."
Gen Ntaganda formerly served as chief of staff to Congolese rebel leader Laurent Nkunda in the Tutsi-dominated rebel militia, the Congress for the Defence of the People (CNDP).
But he joined the national army after splitting in January with Gen Nkunda - who was subsequently arrested in Rwanda.
International Criminal Court judges have said that as deputy head of military operations for another rebel militia, Gen Ntaganda was responsible for seven camps where children were trained.
He is also accused of taking part in that group's attacks when the group used child soldiers.