The site of one of two bomb blasts which occurred on August 11, 2016, in Hua Hin, south of Bangkok, Thailand, in this still image taken from video, August 12, 2016. [Photo/Agencies]

HUA HIN, Thailand - A series of blasts hit three of the most popular tourist resorts in Thailand on Thursday and Friday, killing two people and wounding dozens, just days after the country voted to accept a military-backed constitution in a referendum.

Twin blasts hit the upscale resort of Hua Hin, about 200 km (125 miles) south of Bangkok, on Friday morning just hours after two bombs killed one person and wounded 21 late on Thursday.

Hua Hin is home to the Klai Kangwon royal palace, which translates as "Far from Worries Palace", where King Bhumibol Adulayadej, the world's longest reigning monarch, and his wife, Queen Sirikit, have often stayed in recent years.

Friday was a public holiday in Thailand to mark the queen's birthday, which is celebrated as Mother's Day.

One person died and three people were wounded in one of the Friday morning blasts near a central clock tower in Hua Hin, deputy police spokesman Police Colonel Krisana Pattanacharoen told reporters in Bangkok.

Two small bombs exploded in the tourist beach town of Patong on Phuket island, and two more in Phang Nga, another tourist region in the south, on Friday, police said. One Thai man was lightly wounded in Patong, police said.

Police believe the blasts were acts of "local sabotage" and not linked to international militants, Krisana told reporters.

"It's too soon to jump to any conclusion," he said "But what we know for sure is that the incidents are not linked directly to any kinds of terrorism, in fact it's local sabotage and we are trying to identify those responsible behind the scenes.

"There are no conflicts in the country that may lead to terrorists being in the country. That's why we can say that these incidents are not terrorist attacks," he said.?

Police also said they have not found any evidence that the blasts were coordinated or whether they were related to an insurgency in Muslim-majority provinces in southern Thailand.