Suspected armed gangs have set numerous vehicles on fire to block highways across Guadalajara, Mexico's second biggest city, amid a surge in drug-related violence.

Police confirmed 22 unauthorised barriers were caused by lines of charred, smouldering cars and trucks in the western Mexican state of Jalisco on Saturday. Seven of the roadblocks were in Guadalajara and the rest were in surrounding areas.

Luis Carlos Najera, police chief for Jalisco state, told reporters at a news conference late on Saturday that one man was seriously wounded by gunfire, but no arrests had been made.

"We don't know who is behind this operation," said Najera. He added that all of the roadblocks have since been cleared.

Guadalajara has not seen the level of drug cartel-related violence as other areas, but similar flaming roadblocks shook the city in early March as military forces successfully sought to arrest a prominent cartel leader.

Two people were killed during that operation in Jalisco state, which has been a stronghold of the Sinaloa Cartel since the 1980s, when traffickers first started to use Mexico as a base to smuggle cocaine into the United States.

It has recently seen an upsurge in violence as Sinaloa Cartel gunmen battle rivals from the upstart Zetas cartel, which is displacing older trafficking groups in many parts of Mexico.

More than 55,000 Mexicans have been killed in drug-related violence since President Felipe Calderon took office in December 2006 and launched his crackdown on cartels.

Source: Agencies