The Mexican government vowed Tuesday not to back down in its fight against La Familia drug cartel, despite mysterious banners proclaiming that the brutal gang has dissolved itself.

Lawmakers and drug war experts expressed skepticism about the banners, saying the message could be a ploy to divert the focus of federal security forces away from the cartel, known for beheadings and bold attacks on police and soldiers.

Alejandro Poire, the federal government's security spokesman, "there would be no truce" with La Familia. He did not comment directly on the banners but said La Familia has been weakened since its leader Nazario Moreno was killed in a gunbattle with police last month.

"What is clear is that this criminal organization is weakened and in retreat," Poire said at a news conference.

The banners claiming "La Familia is completely dissolved" appeared Monday on bridges in western Michoacan state, the cartel's stronghold.

Michoacan lawmakers dismissed the significance of the banners, saying there was no way to know the cartel's real intentions, or even if La Familia really wrote the messages.

"I think it's an attempt to divert attention. And besides, we can't be sure that these banners were really put up by that organization or another one," said Juan Carlos Campos, president of the security commission of the Michoacan state legislature. "We can't trust it."

La Familia burst onto the national scene in 2006 when it declared its independence from the Gulf cartel by rolling five severed heads into a disco in the mountain city of Uruapan.

Shortly afterward, President Felipe Calderon — who was born in Michoacan — deployed troops and federal police to Michoacan to fight the cartel. He later extended that increasingly bloody fight to cartel strongholds throughout Mexico.

Although it quickly gained a reputation as one of Mexico's most violent cartels, La Familia tried to cultivate a Robin Hood image, claiming its mission was to protect Michoacan from other drug cartels and petty criminals.

The banners Monday were the latest to appear in Michoacan suggesting the cartel is in disarray. Last year, banners and letters dropped on the streets of some towns claimed the cartel was ready to negotiate a truce with the government.

Raul Benitez, a professor at the National Autonomous University of Mexico who studies the drug trade, said it was unlikely La Familia — one of Mexico's biggest methamphetamine traffickers — was retiring from the drug trade.

But he said the gang may be trying to soften its image.

"La Familia Michoacana is trying to change tactics to try to stop the government from pursuing it because it knows it is a priority for the government," he said. "I don't think it's going to dissolve because it has a lot of interests, but maybe they will stop killing and beheading to stop drawing attention."

The drug war continued in other parts of Mexico:

— Five people were killed in a shooting late Monday at a bar in Mexicali, a sprawling industrial city east of the border city of Tijuana. The Baja California state attorney general's office identified two of victims as a former state investigator and his brother. Another had been arrested in 2008 and allegedly worked for the Beltran Leyva cartel. There were no arrests, and the motive was unclear.

— Five people were killed in the state of Guerrero, which neighbors Michoacan. Three were killed in a gunbattle with troops in the resort city Zihuatanejo. The other two were found dead in their cars, one of them in the resort city of Acapulco.

— Federal authorities seized 23 tons of illegally imported ethyl phenylacetate in the Pacific port of Manzanillo. The chemical — a precursor for methamphetamine — came in a shipment from China, according to a joint statement from the Marines, the Treasury Department and the Attorney General's Office. The port is a major entry point for drugs and precursor chemicals in Mexico. A shipment of 200 tons of several different precursor chemicals were seized in August.