Two Malaysian ministers who should have been quarantining after being exposed to coronavirus voted in parliament in protective gear Monday, triggering an opposition walkout.

The politicians came into contact with Covid-19 patients earlier this month, but officials allowed them to partake in a key budget vote -- provided they wore gowns, face masks, shields and gloves.

But the sitting quickly descended into pandemonium, with opposition MPs shouting out in protest and most deciding to leave the chamber rather than cast their votes.

"It is a black day for democracy in Malaysia because there is no rule of law," opposition lawmaker Xavier Jayakumar told AFP.

However, as well as the health minister and human resources minister, one opposition MP who should have been quarantining also turned up in parliament in protective gear.

The parliament speaker insisted safeguards had been taken, including having the lawmakers transported in an ambulance and placed in a special room, state news agency Bernama reported.

He rejected attempts to stop the vote, and the nine-month-old government easily won after the walkout.

Most MPs had already backed the main budget vote last month, a victory for embattled Prime Minister Muhyddin Yassin whose parliamentary coalition holds a wafer-thin majority.

But officials need to win several more crucial votes related to specific parts of the spending bill. Muhyiddin seized power in March without an election after the collapse of a reformist coalition, but his government is highly unstable and has been accused of lacking legitimacy.