Mr Kony is said to have little interest in the peace process
The UN has insisted it is committed to talks with Ugandan warlord Joseph Kony and his rebel group, despite disbanding its office dedicated to the process.
Uganda's UN envoy Ruhakana Rugunda said Ugandans should rest assured that their government, the UN and international community were working for peace.
He said there was a peace deal on the table waiting for Mr Kony to sign.
Mr Kony's Lord's Resistance Army (LRA) is blamed for displacing and killing thousands in a brutal 20-year conflict.
Channels 'still open'
Although the LRA's stated aim is to install a Bible-based theocracy in Uganda, its rebellion has spread to South Sudan, eastern Democratic Republic of Congo and the Central African Republic.
Former Mozambique President Joaquim Chissano was chosen to head a UN mission aimed at framing a peace deal with the LRA in 2006, but his office was wound down on Wednesday.
Mr Rugunda said there was no longer any need for the mission because there were no peace talks going on.
"There is no reason why President Chissano and his office should remain fully operational when Joseph Kony and his group have opted not to sign [the peace deal]," he told the BBC's Network Africa programme.
But he added: "Ugandans should rest assured that their government, the international community, the UN and Security Council fully support a peaceful resolution of the conflict that Kony is responsible for."
He said the channels were still open for negotiations.
'A sad day'
The talks stalled after LRA negotiators insisted that an international arrest warrant for Mr Kony be withdrawn as a condition of any agreement.
Rights groups have pointed out that all sides reached an agreement to try any cases involving Mr Kony or his men in Uganda.
They say the arrest warrant has been used as an excuse for the LRA not to sign a deal.
In his final briefing to the UN secretary general, Mr Chissano said the LRA leader had given the impression that he had little interest in the peace process.
He said military operations launched by Uganda against the LRA had uprooted and disrupted the rebels.
But he said there had been "vicious" LRA reprisals in DR Congo and South Sudan.
The LRA's chief negotiator David Matsanga said the UN's decision to close its office was a "sad day for the people of the region".
He called on the UN to withdraw the arrest warrant and said the Ugandan government should sign a truce.
"How can Kony sign an agreement when there is no temporary ceasefire?" he said.
As peace talks faltered towards the end of 2008, violence in the region intensified.
Rights groups say the LRA has killed 1,200 people and displaced many thousands more since last December.
It has also stepped up its abductions of children and adults, they say.