The department's director-general Apichai Chawacharoenpan said several geologists on the team had told him they were simply hills of sediment - because the temperature of seawater in the area is not unusually high. 

"Geologists are quite sure they are not mud volcanoes. However, it's hard to be sure because at a depth of more than 600 metres we can only survey with a remote-controlled underwater vehicle."

Dr Anond Sanitwong na Ayut-thaya of Chulalongkorn University, who led the team of Thai and German marine geologists, surveyed the seabed for 1,500 square kilometres at a depth of 1,000 to 2,800 metres at the edge of the continental shelf.

Anond announced on Monday the team had found four "submarine mud volcanoes" about 200 kilometres from the province.

Apichai said the report might scare tourists in Phuket, so he and Anond would hold a press conference to clarify the issue today.

Somsak Wattanaparuda, a geologist from the Mineral Resources Department who joined Anond's team, said what the team had discovered was just the sediment of sandy mud. Unlike a mud volcano, which is a temporary structure created by geologically excreted liquids and gases, the temperature around the sediment is 15-20 degrees Celsius.

Anond yesterday admitted that he had jumped to a conclusion about the mud volcanoes and the team needed further study and evidence. He presumed the mud volcanoes had been created by sediment flowing from the Irrawaddy and Salween rivers in Burma and had piled up for millions of years.

"I want to confirm again that the mud volcanoes won't erupt or create a tsunami," said Anond, adding that he had revealed the discovery not to create panic but to stir people's interest in studying marine geology.