GENEVA (Reuters) - The U.N. human rights office has “strong indications” that Mexican federal security forces are behind a wave of disappearances in and around the city of Nuevo Laredo, a statement from the U.N. human rights chief said on Wednesday.

Mexican officials did not immediately respond to the UN allegations.

The U.N. has documented the disappearance of 21 men and two women in Nuevo Laredo in Tamaulipas State from February until May 16 this year, the statement from U.N. High Commissioner for Human Rights Zeid Ra’ad al-Hussein said.

“Many of these people are reported to have been arbitrarily detained and disappeared while going about their daily lives,” the statement quoted Zeid as saying.

A local human rights organization put the number of disappearances in Nuevo Laredo at more than 40, and the U.N. human rights office received testimonies that they were allegedly perpetrated by a federal security force, often late at night or at dawn, the statement said.

The report is the latest finding by international groups highlighting alleged abuses by the government in its decade-long battle against criminal gangs.

More than 35,000 people have gone missing since former President Felipe Calderon sent military forces to battle drug gangs in late 2006.

There have been more than 200,000 murders since then, with a record number last year fuelling widespread anger with President Enrique Pena Nieto’s ruling party ahead of a July 1 presidential election.

“Mexico is a mutilated country that stinks of blood, where you step on a mass grave wherever you go,” said Fernando Rios, head of local human rights group Red TDT, in response to the U.N report.

Zeid has called on Mexican authorities to end the disappearances “amid strong indications that these crimes have been committed by federal security forces”, the statement said.

“It is particularly horrific that at least five of the victims are minors, with three of them as young as 14. These crimes, perpetrated over four months in a single municipality, are outrageous,” he said.

The authorities had ample information and evidence but had made little progress in investigating, the statement said, noting relatives of those missing had so far found the bodies of at least six victims.

Mexico’s National Human Rights Commission asked the Navy and others to protect the population of Tamaulipas, but at least three disappearances had happened since then.

Zeid said the events were a litmus test of whether Mexico’s new General Law on Disappearances represented real change or a continued failure of justice.

“In the case of enforced disappearance and extrajudicial executions carried out by public officials, it is even more urgent for the state to act to demonstrate that it neither condones nor tolerates the commission of such grave violations,” he said.