Police in the violent border city of Tijuana have their guns back three weeks after being forced to hand them over to federal authorities on allegations on collusion with drug traffickers.

Tijuana Public Safety Secretary Luis Javier Algorri said Saturday that the authorities returned all 2,130 guns to his department.

He said he planned to send a letter to the attorney general's office asking for the results of the investigation to clear up any doubts about his officers. No one from the attorney general's office was available for comment Saturday.

The officers handed in their guns Jan. 4 after President Felipe Calderon sent 3,300 soldiers and federal police to Tijuana to hunt down drug gangs. The soldiers swept police stations and took the guns for inspection to see if they had been used to protect smugglers who traffic drugs into the United States.

The Tijuana police initially stopped patrolling when their guns were taken, saying it was too dangerous, but most later returned to work. In some cases, officers were accompanied by armed state police. Others patrolled in larger numbers than normal. One officer was seen holding a slingshot that he said was for his protection.

Last week, the Tijuana police department announced it had issued some officers slingshots and ball bearings to defend themselves.

Algorri said the drastic action put the city's safety at risk, and cut in half the number of arrests made in January compared to the same period last year.

Five officers were injured by assailants who took advantage of them being unarmed, Algorri said.

He said the city's police officers were inundated with death threats on their radios and blamed drug gangs.

In several neighborhoods, residents took the law into their own hands, grabbing suspects off the street and tying them up before calling police to haul them off.

Dubbed Operation Tijuana, the initiative was part of a major military offensive against drug gangs launched by Calderon, who took office on Dec. 1 promising to crack down on organized crime. Calderon has sent more than 24,000 troops to states plagued by execution-style killings and beheadings as rival gangs fight over marijuana plantations and smuggling routes.

Drug gangs were blamed for more than 2,000 murders nationwide in 2006 and have left a particularly bloody trail in Tijuana, where more than 300 people were slain last year.

Six federal police officers involved in Calderon's anti-drug operation are being investigated for extortion after they were videotaped taking money from a driver in Tijuana, across the border from San Diego.

The videotape recorded by the Tijuana city police department shows the officers at a checkpoint stopping a motorist and searching his vehicle. After a discussion, the motorist was shown giving the police a handful of cash including at least one $100 bill.

The videotape, taken Jan. 17, was released to the media and posted on Mexican news Web sites on Friday.

Calderon narrowly won the presidency last year on a law-and-order platform and has promised to dismantle drug gangs.

Last week, Mexico extradited four alleged drug kingpins to the United States.

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