Perth couple in lockdown at Phuket hotel

A Perth couple staying in Phuket say they have been in lockdown at their hotel for more than five hours due to a suspicious package outside, as Thailand is rocked by a string of deadly attacks.

The series of bombings over 24 hours have killed at least three people and injured dozens more, some of them foreign tourists.

Simon and Nicole Brown from Rockingham said police have cordoned off a 200m perimeter outside their Patong Beach hotel while they inspect the package.

Mr Brown said the hotel has been in lockdown since 8.30am (local time), half an hour after a device went off on Bangla Road.

The couple arrived in Thailand on Wednesday night and felt an unprecedented atmosphere of unease.

"It was the first time in 10 to 15 years of coming here that we mentioned to ourselves that things felt different," Mr Brown told AAP.

"There's a little bit of unease in the air, we just put it down to the recent referendum and the Queen's birthday."

He said that staff have handled the situation very well, yet there was a sense of tension.

"If things escalate we'll be on the next flight home," he said.

Australians have been warned to exercise a "heightened caution" in the country and follow the advice of local authorities.