Updated

Human Rights Watch singled out U.N. Secretary-General Ban Ki-moon for especially harsh criticism Monday as it took world leaders to task for what it called their failure to be tougher on rights offenders.

Ban's office rejected the criticism, insisting that the U.N. chief employs both quiet diplomacy and public condemnation with abusive governments after determining which method will prove most effective in each case.

Human Rights Watch's executive director Kenneth Roth also lambasted the European Union; the E.U.'s first high representative for foreign affairs and security policy, Catherine Ashton; President Obama, British Prime Minister David Cameron, German Chancellor Angela Merkel, and French President Nicolas Sarkozy.

"The use of dialogue and cooperation in lieu of public pressure has emerged with a vengeance at the U.N., from Secretary-General Ban Ki-moon to many members of the Human Rights Council," Roth wrote in the introduction of the group's annual report.

Ban "has been notably reluctant to put pressure on abusive governments," Roth wrote.

"To deserve a second term he will need to be more outspoken and consistent," Philippe Bolopion, U.N. advocacy director for Human Rights Watch said Monday, referring to Ban's likely bid for a second four-year term later this year. Candidates for U.N. chief are nominated by the powerful 15-member Security Council and must be approved by the 192-member General Assembly of member states.

In the report, Roth cited in particular Ban's failure to publicly raise China's rights records or its imprisoned Nobel peace laureate, literary critic Liu Xiaobo, in a meeting with President Hu Jintao late last year.

At the time, Ban defended his handling of a meeting with Hu during an Asia trip, and told reporters upon his return that he spoke about human rights everywhere — including China.

Ban said then that he raised the issue of human rights publicly in Nanjing, Shanghai and Beijing and in private talks with Chinese leaders, whom he didn't name, insisting that diplomacy sometimes must be conducted "in confidence."

"The Secretary-General is a defender of human rights around the world," U.N. Deputy Spokesman Farhan Haq said in response to Monday's report.

"Quiet diplomacy and public pressure are not mutually exclusive," said Haq, adding that Ban has used both methods to gain results with repressive governments.

Defending human rights is among the U.N.'s most important responsibilities, Ban said Saturday at Manhattan's Park East Synagogue, ahead of the next week's International Day of Commemoration in Memory of the Victims of the Holocaust. "As United Nations Secretary-General, I never forget this fundamental mission," he said.

Bolopion told a news conference later Monday that Ban had spoken out publicly on some rights issues, praising him for highlighting abuses in Tajikistan, and for calling all U.N. member states to drop laws that criminalize homosexuality.

Bolopion said Ban also has been outspoken recently on reported rights abuses in Ivory Coast by supporters of the incumbent president and internationally recognized loser of recent elections who refuses to cede power to his elected successor. "We hope this is a sign that he will become more forceful," the rights advocate said.