The government said Tuesday it was stepping up security at detention centers for illegal Cuban migrants after a group of detainees fought police officers and held a guard against his will - the seventh uprising or mass escape by Cubans in a year.

Officials also will deny political asylum to those involved in the latest conflict.

"After these acts, changes will certainly have to be reviewed to increase the level of security" at immigration holding centers like the one in Mexico City where a dozen Cubans rioted and briefly took over the facilities Monday, presidential spokesman Rubén Aguilar said.

The riots are fueled in part by the fact that most Cubans are forced to wait for months inside decrepit Mexican detention centers. The Cuban government often delays recognizing them as a means of punishment for their attempt to leave the island, local officials say.

The Cubans involved in Monday´s uprising were demanding they not be returned to the island, saying they feared reprisals there. Eight Cubans were injured in the scuffle, though their injuries were not life-threatening, the government said in a news release.

"None of these people will be considered in any way for political asylum," Aguilar said.

All seven major incidents at immigration detention centers here in the past year involved Cubans - including riots, and a mass escape in July.

Yet the estimated 500 Cubans detained each year make up a tiny fraction of the approximately 250,000 undocumented foreigners detained in Mexico annually.

Under current policy, Mexico advises foreign consulates that their citizens have been detained, and those consulates have up to 90 days to acknowledge the person in question is a citizen of their country.

Most of the detainees are Central Americans, and they are usually released to their home countries in two days or less.

But the Cuban Consulate here often takes the full 90 days to recognize Cuban detainees, according to a Mexican immigration official who requested anonymity because he is not authorized to speak to the news media.

The Cuban Embassy in Mexico did not immediately respond to requests for comment.

Karina Arias, coordinator for the migrant rights group Sin Fronteras, said that slow consular responses were a factor in keeping Cubans - and a few other nationalities - in detention centers for long periods.

"That is a factor, and the Mexican government has recognized this, not only with Cuban consulates but with other countries as well," Arias said.

A lack of access to information about their cases, overcrowding and unclean conditions at the detention centers also play a role in the riots, she said.

Mexico legally has several choices of action regarding Cuban migrants: deportation to their home country, release to a third country, or asylum in Mexico.