Louise Williams, Jakarta – Riots over rising food prices hit drought-stricken eastern Indonesia over the weekend as the chief of the armed forces led thousands of troops bristling with firepower in a daunting public display in central Jakarta.

Amid the crippling economic crisis, Opposition groups are believed to be planning demonstrations in front of Parliament this week in the lead-up to presidential elections on March 11.

In his speech to an estimated 25,000 military and police personnel charged with securing the elections, General Faisal Tanjung said there were "negative signs" which may lead to "disturbances to national stability". "These disturbances can take the form of demonstrations, mass unrest and radicalism," he told the forces.

They displayed rapid response tactics, including helicopter drops in the city centre, the use of armed personnel carriers and deploying squads of black-clad motorcycle riot troops.

In the eastern Indonesian town of Bima, on the island of Sumbawa, to the east of Bali, at least nine shops were burnt or damaged when local residents rioted over sharply increasing food prices, after marching to the local Parliament.

Witnesses said people attacked shops owned by ethnic Chinese, who have become the scapegoats in unrest which has hit 11 rural towns and cities over the past few weeks as the crisis forces millions out of work and pushes up prices for basic commodities. General Tanjung told his men that "repressive actions" against the people should be the "last resort" but gave no indication of what other methods the armed forces may use to calm an increasingly frustrated public.

The Jakarta military commander, Major-General Syarie Syamsudin, pledged there would be no demonstrations or riots in the capital in the lead-up to the polls, in which President Soeharto is expected to be re-elected unopposed for a seventh five-year term by the rubber-stamp Parliament. Opposition groups are rumoured to be planning to step up demonstrations this week, with the opposition Muslim leader, Mr Amien Rais, due in Jakarta today.

Seven people were arrested in Bogor over the weekend for distributing a speech by the pro-democracy figurehead, Ms Megawati Soekarnoputri, who has forged an alliance with Mr Rais to challenge Mr Soeharto's re-election.

The Legal Aid Foundation head, Mr Hendardi, warned that three days of military exercises were intended to cow an angry public - "to scare the public and stop them demonstrating. But, already, both the lower and the middle classes are suffering due to the economic crisis".

Earlier last week the major wholesaler, Goro, said prices of basic foods would rise by 10 to 15 per cent by mid-week, prices of soap and detergent would rise by 75 per cent, and imported goods by perhaps 300 per cent.