BANGKOK, Thailand — Female tourists visiting the Thai island of Phuket will be given whistles to sound in case of an emergency, the Tourism Ministry said last week after the daylight murder of a Swedish woman.

The whistles are part of a campaign to increase security on Phuket, one of Thailand's most popular tourist destinations, after the killing of 27-year-old Hanna Charlotta Backlund of Sweden, said Tourism Minister Weerasak Kohsurat.

Backlund was stabbed to death March 15 while taking a walk on Mai Khao beach, on the northern tip of Phuket. Her attacker remains at large.

The safety whistles will be shaped like the symbol commonly used to designate women — a circle above a cross — and can be worn around the neck, said Phuket police Maj. Sathabhorn Sangaunsuk, who will be overseeing the project.

The ministry also plans to increase security guards around the island and publish safety manuals that will be distributed to tourists, the minister said in a statement.

Authorities said the plan was just devised and they did not know when distribution of whistles would begin.