Mexico has promised to deploy more troops into a northern border city at the heart of the country's drug war, according to Fernando Gomez Mont, the interior minister.

The decision was announced on Wednesday as a meeting of federal officials in Ciudad Juarez was rattled by bomb scares earlier in the day.

"We aren't going to give up an inch of the city and we will expel them [crime gangs] from Juarez," Gomez Mont said after the meeting, which was heavily guarded by federal police.
   
"There will be a substantial increase in military and federal police presence in the coming weeks."

Threats against public officials have been rising in the region.

Bomb threats

During Gomez Mont's visit to Ciudad Juarez, authorities received bomb threats and found traces of explosives in a vehicle parked at the airport, which was evacuated by soldiers and federal police but reopened by late afternoon.

An unexploded  home-made bomb on Wednesday forced the evacuation of the airport in Ciudad Juarez.

Airport personnel and travellers returned to the airport three hours after the explosive device was found by police, an airport official said.

Security officers have borne the brunt of the surge in violence linked to drug trade [EPA]

Also on Wednesday, a bomb threat led to the evacuation of the Ciudad Juarez courthouse.

No explosives were found on the premises,  security officials, who asked not to be identified, said.

Ciudad Juarez, across from El Paso, Texas, has become Mexico's most violent city as security forces take on drug cartels fighting for control of smuggling routes into the US.

Last week assassins suspected to be acting for drug gangs killed two city council members near Ciudad Juarez.

Separately, a federal police chief resigned, bowing to a crime gang's demand, after his deputy was killed and drug dealers promised murders of police officers every 48 hours.

And late on Sunday, a former soldier attacked a convoy carrying Jose Reyes, the governor of Chihuahua, in what Mexican media speculated was linked to the drug war.

US arrests

The developments come amid arrests in the US of dozens of suspected members of a major Mexican drug cartel.

The US Drug Enforcement Administration (DEA) picked up 52 alleged members of the Sinaloa cartel on Tuesday and Wednesday in the states of California, Maryland and Minnesota as part of what it calls Operation XCellerator.

The Sinaloa drug cartel, along with the Gulf cartel, control most of the flow of illegal drugs into the US and turf wars in Mexico have seen more than 6,000 people killed there in the last year.

Al Jazeera's Franc Contreras, reporting from Mexico City, said the arrests were directed at distribution networks inside the US and that this was a blow to Sinaloa's businesses.

The DEA says the arrests will not stop the cartel's operations in the US, but it will take the traffickers some time to get back on their feet.