Police in southern China say they have detained a man suspected of murdering a billionaire tycoon over a financial dispute by poisoning the cat meat hotpot they shared.

Long Liyuan, who made his fortune running a forestry company in wealthy Guangdong province, died last month after sharing a dinner of cat meat hotpot -- a local delicacy -- with two associates at a restaurant.

On Monday, authorities in Yangjiang city, where the incident occurred, said police had detained one of the associates, local forestry official Huang Guang, on suspicion of poisoning the meal in a row over money.

"Huang, who was helping Long take a lease on a forest, had himself used funds provided by Long. This led to an economic dispute and gave Huang the idea to kill Long with poison," a statement on the official Yangjiang public security bureau microblog said.

Long, a Guangdong provincial peoples congress delegate, and his fellow diners all fell ill after eating the cat meat on December 23, but the other two recovered, the Southern Metropolis Daily newspaper reported on Tuesday.

The paper said Huang had left the meal to make a telephone call and then sneaked into the restaurant kitchen to poison their food. It was not clear why he would poison a meal he then went on to eat.

"He tasted the cat meat, saying it needed to boil longer, then asked the (female) owner of the restaurant to go fetch him three bottled beverages," said the Guangdong-based daily.

"Her (the owner's) husband then went out to buy cigarettes, which is when Huang is now suspected to have slipped in some gelsemium elegans," it added, referring to a poisonous flowering plant native to China.

Before the dinner, the three men had gone to inspect some woodlands that Huang wished to sell to Long, the report said, adding that the official had previously helped the tycoon buy woodlands.

Long or his firm appeared to have paid Huang a total of 3.5 million yuan ($556,000) for various services and Huang had recently been trying to raise more money to settle debts, it said.

Huang had sent a text message to the billionaire giving him his bank details, the paper said.

Long's brother had earlier claimed that the billionaire had been poisoned by a business partner who feared he would report him as corrupt, according to the China Daily.

The family posted a 100,000 yuan reward for further information about his death.

The Southern Metropolis Daily said that during the meal, the third diner, Long's friend Huang Wen (no relation to Huang Guang), mentioned that the cat meat tasted "off" and even joked that it might have been poisoned.

Long's autopsy report will be issued 30 working days after his death, media reports have said.