BUENOS AIRES, Argentina -- Many Argentines armed and barricaded themselves in their homes and stores in fear of looting mobs Tuesday as the nation's celebration of 30 years of uninterrupted democracy were marred by police strikes for higher pay.

Politicians struggled to assert their authority over security forces even as they agreed to salary increases so steep that many provinces won't be able to pay their debts at month's end, adding stress to an economy already suffering from 25 per cent inflation.

President Cristina Fernandez sought to contain the crisis Tuesday night, charging that anti-democratic elements are trying to undo Argentina's hard-won gains. "We must condemn the extortion of those who carry arms to defend society," she declared.

The speech was her first response to a weeklong series of provincial police strikes. As officers abandoned their posts, and in some cases allegedly encouraged violence to pressure authorities, many of Argentina's 23 provinces have endured long nights of chaos as roving groups smash through storefronts and brawl over merchandise.

Hospital and political authorities said at least seven people had been killed, including a police officer in northern Chaco province who was struck by a bullet below his protective vest Tuesday and a store owner whose burned body was found last week in his looted and torched market in Buenos Aires province.

The others allegedly died while looting. One young man was electrocuted while stealing from an appliance store in a rainstorm. Another fell off a motorcycle while carting off a television. A third died in a fistfight over stolen goods inside a ruined store.

Hundreds have been injured and thousands of businesses damaged in the scattered violence. And while most officers were back at work after securing new deals, police uprisings continued Tuesday in several cities. Commerce has been shut down in many places, and even some public hospitals have turned away non-emergency patients for fear of being looted.

With consumer prices soaring, Argentines are accustomed to annual labour protests in which workers threaten chaos if they don't get their way. But strikes by armed police are more ominous in a country where social chaos, police crackdowns and spiraling violence ushered in the 1976 military coup and a world-record debt default in 2001.

"The Argentine people want peace and harmony. Demands of this nature go beyond any expected limits," Cabinet chief Jorge Capitanich said Tuesday. "To be a police officer means carrying weapons to protect the citizens, not to generate anxiety among the people and use extortion against their elected leaders."

To free up cash for the raises, Capitanich announced a three-month delay in payments most Argentine provinces owe this month to the federal government on debts refinanced two years ago.

Human rights groups warned against giving in too easily to the security forces' demands.

The deal Buenos Aires Gov. Daniel Scioli reached with rebellious officers Monday night includes an amnesty for rule-breaking officers, making them eligible for 14,000 promised promotions this month that will raise salaries far above the base pay he promised. The deal also lets officers who retired on 90 per cent pay to return to work at twice their old salaries.

"The weapons given to security forces to protect citizens' life and property cannot be used to force decisions by constitutional powers," warned the Center for Legal and Social Studies, a human rights group that has closely tracked police abuse. "We think it's urgent that the security forces stop intensifying the violence and feeding incidents that pose very high risks to our society and its institutions."

Tuesday marked three decades since President Raul Alfonsin's inauguration ended the 1976-1983 dictatorship. Fernandez invited all political parties to join her on a huge stage in front of the presidential palace for a long night of speeches and music to celebrate democracy's consolidation.

Police strikes and looting were not supposed to be on the program.

The late president's son, legislator Ricardo Alfonsin, and Buenos Aires Mayor Mauricio Macri both said the party should be called off, given the potential for another night of violence. Alfonsin called for "all political sectors to commit together to defend the democracy and its institutions."

The event was set to go on, however, and rival politicians were closing ranks. Capitanich joined Cordoba Gov. Jose de la Sota, whom he initially blamed for starting the crisis by failing to control police in his province.

De la Sota accused police of taking revenge for his closure of brothels that provide illegal profits for corrupt officers. Entre Rios Gov. Sergio Urribarri blamed violence in his province on a small group of officers "with bad records" and accused them of "sedition, a crime against the democratic system."

In province after province, even governors who restored momentary calm by agreeing to big pay raises for police seemed wary of declaring victory. With consumer prices soaring, strikes by public health workers also were spreading, and other public employees were aiming to get raises, too.