One of Yudhoyono's main political allies in the fractured parliament, the Prosperous Justice Party, also criticized the price increases Tuesday, saying the government had yet to work out a detailed plan to compensate the poor.

That was reflected on the streets. In Jakarta, protesters burnt tires and shouted slogans accusing Yudhoyono of failing to defend the poor.

Seeking to cut budget-crippling fuel subsidies, officials late Monday announced domestic fuel prices would rise an average 29 percent. The hikes cover items such as gasoline and diesel and took effect early Tuesday.

Gasoline prices are now 2,400 rupiah (HK$1.4) a liter, up from almost 1,800 rupiah before - still by far the cheapest in Asia.

In Asia's other big oil exporter, Malaysia, which also moved Monday to cut fuel subsidies, unleaded gasoline costs 1.42 ringgit (HK$2.9) a liter.

Phased cuts of subsidies in the past have sparked violence and forced previous presidents to roll back price hikes.

Yudhoyono, Indonesia's first directly elected president, said last week he was ready to become unpopular by sticking to the plan, but with a small support base in parliament he could feel the heat if protests get out of control.

Under pressure from foreign donors, former president Suharto sharply raised fuel prices in 1998, sparking huge street protests that contributed to his downfall that year.

Yudhoyono, who took power in October, had told Indonesians Monday the measures were a hard but necessary step. Economists agreed, saying Indonesia needs to free up funds for infrastructure and development spending.

The subsidies last year cost the state 59 trillion rupiah. Officials said the cuts would mean a fuel subsidy bill for the state this year of 39.8 trillion - still 10 percent of budget expenditure.

Indonesia is Asia's only member of the Organization of the Petroleum Exporting Countries but was a net crude oil importer in some months last year due to production problems and low investment.

Under the hikes, gasoline prices increased by 32.6 percent and automotive diesel fuel by 27.3 percent. Household kerosene was left unchanged.

Some officials have said a fund would be created from part of the saved subsidies to help those worst hit by the rises, with 16.4 trillion rupiah channeled to the poor in medical, rice, social and education assistance.

But Rama Pratama, a member of parliament's budget commission from the Prosperous Justice Party (PKS), said details of the scheme were unclear.

``PKS rejects the fuel price increases because the government has not prepared details of the compensation program, to show they can reach the right target,'' he said.

``The government also has no clear scheme to deal with the inflation that will be triggered by simultaneous increases in the prices of staple goods.''

The price rise also prompted an angry reaction from two parliamentary factions of the National Mandate Party and the United Development Party (PPP) who want an investigation launched into the increases.

PPP deputy chairman Djoko Susilo said his faction would bring forward a motion in parliament to initiate the probe, and deputy house speaker Sutarjo Suryoguritno declared the motion would have his support.

Unanswered queries included real fuel production costs for state oil and gas firm Pertamina, details on the allotment of government compensation packages and the lack of planned subsidies for public transportation.

Senior economy minister Abu Rizal Bakrie said the increase would ensure a better future for all. The government was ready to face the parliamentary investigation, he added.

Tuesday's street protests, meanwhile, went beyond slogans. A fuel tanker was hijacked in Jakarta, protesters burnt tires and authorities were forced to close off streets.

National Police Chief General Dai Bachtiar has ordered two-thirds of his officers to remain on standby in case of violence.

In Jakarta, more than 13,000 police, soldiers and city personnel were on standby.

Public transportation was paralyzed in nearby Bogor and in Palangkaraya in Central Kalimantan, Palu in Central Sulawesi, Serang in Banten province and Kupang in West Timor as operators demanded higher fares. Prices of essential and non-essential goods increased in several Jakarta markets by up to 100 percent following the price rise, Antara news agency reported.REUTERS, AGENCE FRANCE-PRESSE