Buddhist monks chanted around a spaceship-shaped golden shrine, as a controversial Thai sect burned 330,000 candles attempting a Guinness World Record for the largest flaming image on Thursday -- all to commemorate Earth Day.

The candles, in the shape of a map of the world and a Buddha figure, were arranged around the central shrine at the Dhammakaya sect's 78-acre compound, north of Bangkok.

"Cleanse the mind, cleanse the world" was also spelled out in the flickering light, and organisers said the objective was "to encourage people of any nationality, race and religion to join together in the activities of chanting and group meditation, sharing loving kindness".

The ceremony was timed to coincide with Earth Day, a worldwide event which aims to boost awareness about ecological issues -- raising questions about whether the burning of so many candles was in itself bad for the environment. 

"We will have to see what kind of products these candles are made from. Some substances are not harmful, while others could contribute to air pollution," Thai environmental health expert Suwimon Kanchanasuta from Mahidol University told AFP.

Devotees who spoke to AFP said they had made the candles themselves, and that no "dangerous materials" were used. 

"We only lighted it for a brief moment and our one-hour good intention will be felt by the people all over the world and make them pay attention to what we’re intending to show here," Juntira Komasatit, a 47-year-old Dhammakaya follower, said. 

IQAir, a Swiss-based air quality technology firm, notes most candles are made from paraffin, a petroleum byproduct.

"In addition to releasing toxic chemicals, burning paraffin wax produces soot with particles that can remain suspended in the air for hours," its website states.

It was not immediately clear whether the world record had been achieved, or how it was being monitored. 

The Dhammakaya sect is a wealthy Buddhist order founded in 1970, which was steered to riches by the septuagenarian monk Phra Dhammachayo.

From unorthodox animated Buddhist teachings to alleged ties with former premier Thaksin Shinawatra, the Dhammakaya temple's reputation has been embedded with controversies.

In 2017 Phra Dhammachayo was the subject of a massive police hunt at the Dhammakaya temple complex, with officers uncovering secret tunnels as they sought his arrest over allegations of money laundering and a massive embezzlement of $33 million. 

The former abbott, who was 72 at the time, remains at large.

Buddhist authorities have accused Dhammakaya of peddling a pay-your-way to nirvana philosophy, spreading the sect's popularity through public relations events.

The temple denies the allegations and says the charges are politically motivated.

It has since quietly rebounded and continues to hold several high-profile annual events.

With "world peace as inner peace" as its motto, the sect has 84 centres in 31 countries worldwide, from Belgium and Canada to the Solomon Islands and South Africa.