Protesters watch as the headquarters of the ruling Mongolian People's Revolutionary Party burns in Ulan Bator, the capital of Mongolia, on Tuesday. (Jude Mak/Associated Press)

A state of emergency has been declared in the Mongolian capital of Ulan Bator after violent protests against alleged electoral fraud left five people dead and hundreds injured.

President Nambaryn Enkhbayar declared the beginning of a four-day state of emergency late Tuesday after protesters torched the headquarters of the ruling party, the Mongolian People's Revolutionary Party, and attacked other government buildings.

Several floors of the party's headquarters were burned, and looters grabbed paintings and televisions from government buildings.

Protesters also attacked the General Election Commission offices Tuesday night, demanding that officials resign over alleged voting irregularities in Sunday's parliamentary election, which largely focused on how to share the country's mineral wealth.

The city was also placed under a curfew and parts were cordoned off.

"Police will use necessary force to crack down on criminals who are looting private and government property," said Munkhorgil, the minister of justice and home affairs, who like some Mongolians goes by one name.

President appeals for calm

About 220 civilians and 108 servicemen were injured in the clashes and about 700 protesters have been detained, said Munkhorgil.

The president, a ruling party member, acknowledged the protesters' complaints over results of the election, but appealed for calm.

"Let's sit down and solve the election fraud," he said on national TV.

Fraud allegations originally centred on two districts in Ulan Bator that were awarded to the ruling party, but were contested by two popular members of the Civic Movement party.

Protesters later called the entire election into question, with opposition Democrats saying that their party, not the Mongolian People's Revolutionary Party, won the poll.

According to preliminary results, the MPRP — which also governed the country when it was a Soviet satellite — won 46 seats, more than half the 76 seats in parliament.

Mongolia, a mostly poor country sandwiched between China and Russia, is struggling to modernize its nomadic, agriculture-based economy. The government says per capita income is just $1,500 US a year in the country of about three million people spread across an area about three times the size of Spain.

The two main political parties focused their campaigns on how to tap recently discovered mineral deposits — including copper, gold and coal — but disagreed over whether the government or private sector should hold a majority stake.

The MPRP wants the government to hold the majority stake, while the Mongolian Democratic Party says private Mongolian companies should be able to hold it.

With files from the Associated Press