PARIS — A judge at the United Nations war crimes tribunal in The Hague has exposed a deep rift at the highest levels of the court in a blistering letter suggesting that the court’s president, an American, pressured other judges into approving the recent acquittals of top Serb and Croat commanders.

The letter from the judge, Frederik Harhoff of Denmark, raised serious questions about the credibility of the court, which was created in 1993 to address the atrocities committed in the wars in the former Yugoslavia.

Even before Judge Harhoff’s letter was made public Thursday, in the Danish newspaper Berlingske, the recent acquittals had provoked a storm of complaints from international lawyers, human rights groups and other judges at the court, who claimed in private that the rulings had abruptly rewritten legal standards that had been applied in earlier cases.

Experts say they see a shift in the court toward protecting the interests of the military. “A decade ago, there was a very strong humanitarian message coming out of the tribunal, very concerned with the protection of civilians,” said William Schabas, who teaches law at Middlesex University in London. “It was not concerned with the prerogatives of the military and the police. This message has now been weakened, there is less protection for civilians and human rights.”