One of Mexico's leading regional newspapers has said it is shutting temporarily amid continuing attacks and threats from suspected drugs gangs

BBC News:

The offices of Cambio Sonora have come under grenade attack twice since April

The newspaper is based in Sonora state on the US border, which last week saw a battle between drug gangs and security forces that left 22 people dead.

Rising drug-related violence in Mexico has prompted President Felipe Calderon to send troops to several states.

Speaking on Thursday, Mr Calderon insisted he would not abandon his policy of sending the army in to tackle drug-traffickers despite growing criticism.

Mr Calderon, who has been in office nearly six months, has sent more than 20,000 troops throughout the country to battle the drugs cartels who have been fighting each other for control of territory and drug routes.

About 1,000 people have been killed in drug-related violence so far this year.

Last week, unidentified attackers threw a grenade at Cambio Sonora's offices in the state capital, Hermosillo, following a similar attack in April - both caused minor damage.

The head of the company that publishes the newspaper said these attacks were clearly designed to intimidate the staff and create an atmosphere of fear and terror.

"With profound sadness, we have to acknowledge that in Sonora the dangers and insecurity that confront...Cambio Sonora have surpassed the limits that common sense, patience and human sensitivity can tolerate," said Mario Vazquez Rana.

The newspaper had already halted most of its investigations into organised crime or drug trafficking because of the rising level of violence.

Media rights groups consider Mexico to be one of the most dangerous countries for reporters in the world.

Seven journalists have been killed since October and earlier this month, a TV reporter and cameraman disappeared in the northern city of Monterrey provoking fears they were abducted by a criminal gang.

Mexico newspaper is drug war casualty