Gunmen assassinated a commander of Mexico City's anti-kidnapping police on Friday, the fourth top police authority slain in 10 days here as the toll from a rising organised crime wave hits top brass.

One day after acting federal police chief Edgar Millan was brutally murdered, four gunmen in a truck shot and killed anti-kidnapping commander Esteban Robles, authorities said.

Robles was rushed to hospital after the attack on Friday but did not survive.

The violence, believed to be mostly-related to the government's stepped up fight against drug trafficking, saw a new grim chapter on Thursday in Mexico City as gunmen ambushed Millan (41) and assassinated him in his home.

"Mexico has lost one of its most valuable men, a security professional at the service of the nation," a statement from the Public Safety office read. A suspect was detained hours later.

The office of Mexico's president noted that Millan had played a key role in the anti-organised crime crackdown involving more than 36 000 military troops.

Since December 2006, President Felipe Calderon's federal government has deployed 36 000 military troops and thousands of police around the country in an operation aimed at clamping down on organised crime.

Officials claimed the rising death toll showed that criminals were panicking about the clampdown, and trying to cling to control of their narcotics distribution networks especially in northern states which border the United States.

Robles and Millan's killings were not the first of a senior anti-crime authority. Top federal organised crime investigator Roberto Velasco was gunned down at his home in the capital 6 May. He died in hospital shortly thereafter.

Federal authorities have not said how many police have been killed in the operation. On 6 May, the police commander for the sex crimes unit in Ciudad Juarez, Berenice Garcia (32) was shot dead at her home by a group of gunmen. Hundreds of women have been killed since the 1990s in mostly still-unsolved cases in the northern city.

Last weekend at least 34 people were murdered, bringing the figure to more than 1100 for this year, according to local media reports. In just one incident in Guerrero state 60 gunmen stormed a ranch, killing 10 people.

AFP