The US embassy in Colombo warned Thursday its citizens visiting Sri Lanka to avoid travelling alone in tuk-tuks after a spate of sexual harassment complaints.

The embassy, in a message posted on its website, advised women against hailing the brightly-coloured autorickshaws used widely to get around in Sri Lanka.

“The US embassy Colombo has been made aware of an increase in incidents involving tuk-tuk drivers in the Colombo area inappropriately touching female passengers,” said the statement.

“Females should avoid travelling in tuk-tuks alone in Colombo.” Many of the reported incidents occurred at the end of a ride, the embassy said. Those opting to use tuk-tuks were requested to take photos of the driver and registration plate before boarding.

There are some 1.2 million autorickshaws in Sri Lanka, most used as taxis in a country where public transport is often unreliable and overcrowded.