Motorcycle riders crashed after skidding on an oil slick left by a bus in Thailand.

Suwit Rungroj, 37, was on his way to work and had taken the busy Debaratna Road in Samut Prakan province on March 10.

He was following a bus, which had left a trail of black fuel several hundred metres on the tarmac.

As he sped across the road, he and another motorcycle rider were sent skidding across lanes when they slipped on the streak of oil. Oncoming cars swerved to avoid them as they went rolling from their bikes.

Suwit was rushed to the hospital for injuries on his left leg.

He called his wife Darini Nueangthong, 39, to bring his documents to the hospital, but she too crashed hours later while riding her motorcycle.

She was passing through an alley and had driven over sand used to cover up the earlier oil leak, causing her to lose control.

Paramedics were notified and arrived at the scene at 9:30 AM.

They found Darini with a swollen left cheek, grazed knees, and several abrasions on her body. Her Honda Click motorcycle was slightly damaged.

She was given first aid before being taken to the Bang Bo Hospital.

Bystander Chanikarn Sripimsor, 30, said she saw Darini crash after passing through the sand-covered section of the alley.

A nearby convenience store owner said she tried to warn passing drivers to be careful of the oil slick, as they might mistake it for a simple water stain.