Bolivian police fired water cannons Wednesday at disabled protesters, many of them wheelchair-bound, who tried to get near the presidential palace to demand increased benefit payments.

Disabled protesters have been camped out for a month in tents near the Plaza de Armas, the seat of executive and legislative power in Bolivia, to condemn their paltry state benefits -- just $14 a month.

President Evo Morales's government is rejecting calls to quintuple the benefits, responding to the demonstrations by putting up metal barricades to block off the square.

The interior ministry said a group of protesters tried to breach the gates by attacking police with "knives, punches and noxious chemicals," prompting officers to break them up with high-pressure blasts from water cannons mounted on trucks.

Several disabled groups have struck deals with the government in recent weeks, but one hardcore contingent has vowed to continue protesting.

There are some 388,000 disabled people in the poor, landlocked South American country, according to government figures.