A woman sustained 90 per cent burns after setting herself on fire outside the Bulgarian president's office in the capital of Sofia.

Bystanders rushed to put out the fire after the 38-year-old set herself alight in the street, saving her life.

The woman is now in critical condition after the incident, which coincided with President Rosen Plevneliev discussing the formation of a new government following an inconclusive election last month.

Bystanders attempt to put out flames engulfing a 38-year-old woman after she set herself on fire in front of the Bulgarian presidency building in Sofia

According to witnesses, the woman stepped out of a car in front of the building and set herself alight after pouring a flammable liquid over her hair and body.

'The woman, a 38-year-old, was taken to hospital. She is in very serious condition,' an interior ministry spokeswoman said.

A doctor at an emergency hospital in Sofia told reporters the woman, named locally as Lidia Petrova, had 90 per cent burns and remained in critical condition.

The doctor said she has a record of mental illness, but did not elaborate.

Serious injury: It is not yet known why the woman, named locally as Lidia Petrova, set herself on fire

Fire: The woman is now in critical condition in the hospital, after sustaining burns on 90 per cent of her body

Distress: Doctors in Sofia later told local media that the woman had a history of mental illness

The incident took place as President Plevneliev was discussing forming a government following the inconclusive October 5 snap poll in Bulgaria, the poorest country in the European Union.

The centre-right GERB party won the vote, but lacks a majority, and is currently holding talks to form a minority government and secure outside support from a nationalist party and a centre-left faction.

In the first months of 2013, Bulgaria was rocked by demonstrations which brought down the centre-right GERB government.