The British co-founder of online fashion retailer Asos has died after falling from a high-rise apartment balcony in Thailand, according to reports. 

Quentin Griffiths, 58, who was born in London, is said to have mysteriously plunged from the 17th floor of his condominium in Pattaya.

Emergency services found the millionaire's body on the ground below his balcony.

Officers said there were no signs of a disturbance inside the apartment, but added that foul play has not been ruled out pending further forensic tests. 

His exact cause of death will not be determined until a full post-mortem examination is completed, a process that could take several months.

The tragedy comes amid an alleged ongoing dispute with his Thai ex-wife, who accused him of stealing £500,000 from a company they operated together.

Last year, Griffiths was reportedly arrested and questioned by detectives after she alleged he had forged documents to sell land and shares in the business without her knowledge.

Griffiths denied the allegations and was released after questioning.

The investigation was continuing at the time of his death, according to reports.

A source close to the family told The Sun: 'It's a real mystery. The phrase "suspicious circumstances" has been used but we just don't know yet.'

Griffiths helped launch Asos in 2000 alongside Nick Robertson and Andrew Regan, and remained there until 2005.

The company grew into a £3billion global retailer, with the Princess of Wales and Michelle Obama among those to have worn its own-label designs.

A former advertising executive, he stepped down as marketing director after four years. 

He later made £15million from share sales in 2010 and received a further stock windfall in 2013.

He later sued his accountants at BDO, saying he had been given the wrong advice on how to avoid tax on the sale. 

The bungled advice, he claimed, ended up costing him more than £4million in tax on the sales of more than £10million of shares in Asos and Achica, an online retailer he also co-founded. 

The father of three then moved to Thailand around 2007. 

After divorcing his first wife, he married a Thai woman and had a son and daughter. The couple separated several years ago.

The Daily Mail has approached the Foreign Office for comment.