Human Rights Watch has criticised a United Nations probe into allegations against Pakistani peacekeepers in the Democratic Republic of Congo.
Pakistan is the largest contributor to the UN peacekeeping effort
The rights watchdog said in a letter to the UN the report should be the start, not the end of a process.
After an 18-month investigation the UN concluded that only one man was involved in gold smuggling.
It also refuted allegations that UN staff were involved in supplying arms to militia.
In a letter to Jean-Marie Guehenno, the under-secretary-general for UN peacekeeping operations, Human Rights Watch criticised him for saying that the matter "is now closed".
"A report confirming illegal acts by UN peacekeepers is not the end of a process, but surely only the beginning," said Kenneth Roth, the organisation's executive director.
"The UN should follow through on the results of its own investigations."
"Human Rights Watch has repeatedly acknowledged the important and positive role played by the UN peacekeeping force in [DR] Congo in recent years.
"Nevertheless, the slow process of this investigation and the continued lack of action raise important questions about how the United Nations investigates itself," the letter said.
On 13 July 2007, the United Nations inquiry had confirmed that a Pakistani peacekeeper in DR Congo was involved in smuggling gold.
A contingent of Pakistani peacekeepers was accused of selling gold and guns between 2005 and 2006 to Congolese militia groups they were meant to disarm.
The investigation, which began in early 2006, found no evidence of gun-running.
Pakistani officials have previously denied all the accusations, describing the allegations as "baseless".
In May the UN said it would seek to discipline anyone who had compromised peacekeeping in DR Congo by trafficking in gold or guns.
Mr Guehenno told the BBC on 13 July: "The investigation has found no evidence of gun smuggling but it has identified an individual who seems to have facilitated gold smuggling.
"We have shared the report with the concerned troop contributor and I'm confident they will take the required action. This issue is closed."
This is the latest in a series of scandals involving UN peacekeepers.
Mr Guehenno said he thought UN peacekeeping was overstretched, with 100,000 peacekeepers in the field but a support staff of just 1,000 at headquarters.
That was a factor in continuing problems with discipline, he added.
Although the UN can send misbehaving peacekeepers home, countries providing troops are responsible for their own conduct.
The Pakistani battalion at the centre of the claims was based in and around the mining town of Mongbwalu, in the north-east of the country, in 2005.
They helped bring peace to an area that had previously seen bitter fighting between the Lendu and Hema ethnic groups.
But witnesses said Pakistani officers had also supplied weapons to notorious militia commanders in return for gold.
As the trade developed, the officers allegedly brought in the Congolese army and then Indian traders from Kenya.
The UN began a major investigation after being alerted by Human Rights Watch in late 2005.
A UN official connected with the inquiry has previously told the BBC there seemed to have been a plan to bury the results, in order to avoid alienating Pakistan - the largest contributor of troops to the UN.