Police shot dead in Mexican city

Two police officers have been shot dead in a northern Mexican border city which is the focus of a major crackdown on drug trafficking.

It raises to five the number of officers murdered this week in Nuevo Laredo, an important transit point for drugs entering the US.

The Mexican army and federal agents have been sent in to restore order and investigate police corruption.

The operation has resulted in 1,000 arrests but few cocaine seizures.

Turf war

Ricardo Uvalle Escobedo and Jose de Jesus Morin Salinas were killed by gunmen in separate incidents on their way to work on Wednesday.

On Tuesday night, two other officers, Daniel Juarez and Carlos Manuel Alvarez, were killed when their car was sprayed by automatic gun fire.

On Sunday, police agent Jose Noel Vives died after he was shot more than a dozen times as he left his fiancee's house.

The shootings bring to 13 the number of police killed since January in Nuevo Laredo, which lies across the border from Laredo, Texas.

The city is in the grip of a turf war between drug cartels which has claimed dozens of lives this year.

The police force was suspended while it was investigated for links between officers and the drug cartels.

At least 89 agents have already been fired and about 600 others are still under investigation.