BANGKOK, Thailand – Police on a scenic Thai resort island searched hotels and workers’ residences Tuesday looking for clues into the slayings of two British tourists whose nearly naked, battered bodies were found on a beach a day earlier.

More than 70 police officers were deployed to Koh Tao, a popular diving destination in the Gulf of Thailand, as the country’s leaders called for a swift investigation into the brutal killings that were a new blow to Thailand’s tourism industry.

“This should not have happened in Thailand. It will affect our image in the eyes of international countries,” said Prime Minister Gen. Prayuth Chan-ocha.

He also urged the media to warn tourists about travel safety in Thailand.

“In their countries, (foreigners) can travel wherever they want, so they thought it is safe, but in our country, there are still problems. There are different types of people, so they have to be careful,” Prayuth told reporters. “Those related must warn them and this incident has to be investigated because Thai people won’t tolerate this.”

Defence Minister Prawit Wongsuwan said police were working “to make an arrest as soon as possible.”

The bodies of Hannah Witheridge, 23, and David Miller, 24, were discovered Monday morning in a rocky alcove along the shore close to the hotel where they were staying.

Both had deep wounds and gashes to the head and face that police believe were inflicted by a bloodied hoe found near the bodies.

The pair travelled to Koh Tao with friends and met each other on the island while staying in neighbouring rooms at Ocean View Bungalows, said police Maj. Gen. Kiattipong Khawsamang.

Police said an Asian-looking man seen on closed-circuit camera footage was a prime suspect, but investigators were pursuing several leads.

“We are focusing on migrant workers because of the surrounding witnesses and evidence, including the video footage,” Kiattipong said. “We are sweeping hotels, bars, businesses and residences of migrant workers on the beach to find the suspect.”

Another police official, Col. Prachum Ruangthong, said investigators were also looking for a group of bar employees and had questioned a group of foreigners as well.

“This morning we surrounded three locations, including the residences of migrant workers, to search and collect DNA,” Prachum said.

On Monday night, about 100 local residents gathered on Sairee Beach for a candlelit vigil and said prayers for the young British couple close to the spot where their bodies were found.

The bodies of Witheridge, from Great Yarmouth, Norfolk, and Williams, from Jersey, Channel Islands, were sent Tuesday to forensic police in Bangkok.

The attack came amid government efforts to revive Thailand’s tourism industry after a military coup in May ended prolonged, sometimes violent political protests. Martial law remains in effect in many parts of Thailand.

Koh Tao, which is about 410 kilometres (250 miles) south of Bangkok, is a quiet, small island a short boat ride from the better-known Koh Samui and Koh Phangan, the latter known for its raucous “full moon” parties that attract young foreigners and Thais.