The chief prosecutor of the U.N. Yugoslav war crimes tribunal voiced concern Monday at the "destructive" effects of a critical letter written by one the court's judges that suggested the United States may have tried to influence verdicts.

The letter, which leaked into the media earlier this month, offers no evidence of possible outside interference, but even so it has ignited a storm of criticism of the court among survivors of the Balkans wars and led to calls for the tribunal's American president, Theodor Meron, to quit.

Washington has emphatically rejected the suggestions in the letter written by Danish Judge Frederik Harhoff in the aftermath of three high-profile acquittals of senior suspects from Serbia and Croatia of orchestrating atrocities.

"I am sitting here with a very uncomfortable feeling that the court has changed direction under the influence of pressure from 'the military establishments' in certain dominant countries," a translation of the Danish-language letter says.

Elsewhere, the letter reads: "Have any American or Israeli officials ever exerted pressure on the American presiding judge (the presiding judge for the court that is) to ensure a change of direction? We will probably never know."

U.S. Ambassador-at-Large for war crimes issues Stephen J. Rapp told The Associated Press in an email last Friday that U.S. officials "respect the independence of the tribunals (for Yugoslavia and Rwanda) and do not seek to influence their decisions in any case."

"We wish always to see a fair process with guilt decided solely on the evidence based on legal standards that are consistently applied," Rapp added.

The tribunal's press office denied repeated AP requests to interview Meron; Harhoff, when reached by phone, also refused comment.

In the first public comment about the scandal by a senior official of the tribunal, Chief Prosecutor Serge Brammertz said Monday he is "concerned about destructive elements in the debate" that followed the letter's publication. He also announced he will appeal the most recent acquittal and is considering seeking a review of another of the cases.

The first of the three shock acquittals came last November when the appeals chamber led by Meron cleared two Croat generals, Ante Gotovina and Mladen Markac, of atrocities against Serbs in a 1995 offensive. It was followed by another acquittal by Meron's appeal's chamber of Gen. Momcilo Perisic — a former chief of staff of the Yugoslav National Army who was convicted in 2011 and sentenced to 27 years for aiding and abetting Bosnian Serb forces responsible for vicious crimes throughout the 1992-95 Bosnian war.

Finally, last month, a tribunal trial chamber acquitted two former senior members of Serbia's secret service of arming and supporting murderous Bosnian Serb paramilitaries during the wars in Bosnia and Croatia.

The judgments were seen by experts as significantly raising the legal threshold for holding commanders responsible for the crimes of their subordinates and reversing years of jurisprudence at the ground-breaking 20-year-old court.

The acquittals of Perisic, Jovica Stanisic and Franko Simatovic coupled with Harhoff's letter outraged Bosnian survivors, who are now urging Meron to resign.

"If he does not do it himself, we will make sure he will be replaced and we will even initiate a legal procedure," said Satko Mujagic, a survivor of the notorious Serb-run Omarska prison camp during Bosnia's 1992-95 war.

The Association of Victims and Witnesses of Genocide, which groups of about 15 different associations, also called on the American judge to quit.

And it is not only victims who are concerned by the letter.

Prof. David Crane, an international law expert from Syracuse University College of Law and former prosecutor of the Special Court for Sierra Leone, said the tribunal has to publicly establish the truth or risk an indelible stain on its reputation.

"If this type of alleged — and I underscore alleged — manipulation if going on this is really quite problematic; it brings the whole system into question," said Crane. "And it certainly is a huge black mark on the ICTY. That's why I'm saying they've got to move quickly, neutrally, openly and fairly to get to the bottom of this so they can move on."

Crane said he had never been put under any pressure by U.S. authorities during his time with the Sierra Leone court.

Another tribunal watcher, Dov Jacobs, an assistant professor of international law at Leiden University, agreed that there could be cause for an investigation.

"If they're asking the court to investigate the fact that Judge Meron might have received directions from his government then I think that's fair enough," he said. "There's no evidence so far, but that would be a legitimate cause for investigation."

But Jacobs said the recent acquittals of top Serbian officials for involvement in Bosnian atrocities was in line with another ruling — by the U.N.'s highest judicial organ, the International Court of Justice — that in a landmark 2007 ruling refused to point to Serbia as chief architect of the 1995 Srebrenica massacre in which some 8,000 Muslim men and boys were murdered by Bosnian Serb forces.

"The ICJ clearly said that Serbia did not commit genocide, was not an accomplice in genocide and only — if you can use the term — only failed to prevent genocide," he said. "So there is a consistency there."


Associated Press Writers Jan Olsen in Copenhagen, Denmark, and Aida Cerkez in Sarajevo, Bosnia, contributed to this story.