A motorcyclist was critically injured when he was struck by a falling tree while riding to work.

Mr Lee Kar Choon, 23, a Malaysian, was on his way to his job in the production line at a food-manufacturing factory in Senoko, when the accident happened.

"He was just five minutes away from his workplace," his brother-in-law, Mr Jonathan Poh, 27, told The Straits Times over the phone.

The retail associate said the accident happened between 6.30am and 7am a week ago in Admiralty Road West, during heavy rain.

His family still does not know what actually happened and is appealing for anyone with videos or photos of the accident to come forward.

The Straits Times understands the tree which fell was a casuarina and the authorities are investigating the matter.

"He was taken to Khoo Teck Puat Hospital, where the staff contacted his workplace, which then contacted me," said Mr Poh.

He said Mr Lee was taken to the hospital in a coma, and had to be operated on to remove a blood clot in his brain.

"The doctor told us that his condition is now quite stable, but still critical," Mr Poh said.

As he also suffered a shattered chin bone and cracked cheek bone in the accident, he has to undergo more operations, with the next tomorrow for his chin.

Mr Poh understands that his brother-in-law, who is currently in the intensive care unit (ICU), was found lying on the road, with the tree "right beside his head".

His motorbike, which is black in colour with orange designs, lay some distance away.

"The tree had fallen from the opposite side of the road, so it blocked off two lanes," he said.

Mr Lee has been working here for close to five years. "Up until three years back, he had rented a flat here. But then he had a daughter, so the three of them moved back to Johor Baru," said Mr Poh.

Since then, Mr Lee's routine had been to travel across the Causeway every day, except on Sundays, returning between 5.30and 6 in the evenings.

"The road where the accident took place is on the route Malaysian workers commonly take to get to the factory areas," said Mr Poh.

When they received word of the accident, Mr Poh and his wife drove across the Causeway with Mr Lee's wife and daughter.

Mr Lee is the younger brother of Mr Poh's wife.

Mr Poh said the accident would place a financial burden on his brother-in-law's family.

"His wife is especially worried because, while the medical expenses now are borne by his company, the road to recovery is quite long," he explained.,

"While recovering, he can't work, so they are trying to figure out their finances now."