A panel appointed by Sri Lanka's Human Rights Commission which examined 327 cases of disappearance between 1990 and 1998 was unable to trace a single victim, but found alleged perpetrators had developed amnesia.
"We have faulted the police and armed forces for institutional racism, we fault the LTTE (Liberation Tigers of Tamil Eelam) too on this account for specially targeting Muslim leaders for arrest," the report, which was released on Wednesday, said.
Sri Lankan Tamils constitute about 12.6% of the 18.6 million population, while Muslims make up about 7.5%. The Sinhalese are the majority community, making up 74% of the population.
A member of the investigating panel, MCM Iqbal said a member of the LTTE had been identified by Muslims as being responsible for the disappearance of 35 Muslim men in 1990, but the man could not remember anything.
"We have faulted the police and armed forces for institutional racism, we fault the LTTE (Liberation Tigers of Tamil Eelam) too on this account for specially targeting Muslim leaders for arrest"
Sri Lankan Human Rights Commission report
"We have no evidence to come to any conclusion except to hold the LTTE responsible for the disappearance of each of these 25 Muslims, the complaints in respect of which evidence was heard by the committee.
"Nothing could be said about the remaining 10 complaints regarding Muslims who disappeared as no evidence was available to the committee," said the report.
Iqbal added the probe team had identified 44 military personnel alleged to have committed excesses.
As a result of the hearings, the team managed to secure 50,000 rupees ($531) for the families of two children shot and killed by a soldier in the northern peninsula of Jaffna.
The Tigers and the government are currently engaged in a Norwegian-backed peace process with a ceasefire holding since February last year.
Both have agreed to commit to a human rights declaration, but a suspension of direct face-to-face talks since March has held up progress.
Sri Lanka's missing
The international Committee of the Red Cross said in February that it had begun reopening files on about 11,000 people missing in Sri Lanka and would set up a system to establish the fate of the victims.
The Tamil Tigers have been
condemned for attacking Muslims
Amnesty International, in a 1997 report said nearly 600 Tamils who disappeared after being taken into military custody in the Jaffna peninsula in 1996 had been killed.
"There is no evidence to suggest that sanction for the 'disappearances' came from the political leadership," the report said.
"But the Sri Lankan government reacted too slowly to well documented reports of a rise in disappearances."
The LTTE also came under criticism for "indiscriminate killings of civilians during attacks on checkpoints or army patrols and summary executions of suspected informants", in the Amnesty report.