MANILA, Philippines: The steam baths at this spa could get a little too hot for comfort.

The Philippine environment secretary said Tuesday he will travel to a restive volcano to check whether a spa being built by South Korean investors on the edge of its crater lake is safe and adheres to construction guidelines.

Complaints made by environmental groups and villagers opposing the spa's construction prompted a senator to call for an investigation into land titles on the main crater of the scenic, low-slung Taal volcano south of Manila.

Environment Secretary Angelo Reyes said his department issued a certificate confirming that the spa's engineering plan conforms with environmental regulations, but that he would travel to the site this week to check the project's compliance.

Taal, in Batangas province, has shown signs of restiveness since 2005. Two earthquakes, accompanied by a rumbling sound, jolted the island Sunday, alarming villagers but causing no injuries or damage while focusing public attention on the little-known spa project. It was not immediately clear if the location on the crater lake was essential to any of the treatments to be offered at the spa.

Sen. Pia Cayetano, a pro-environment activist, said she would initiate a probe into how a number of families were able to secure land titles along Taal's crater lake and nearby areas, which are considered public land.

Cayetano said the government should not allow the spa's construction "because it will surely bring disaster to both nature and human beings."

Talisay Mayor Florencio Manimtim said the spa was being built on a six-hectare (15-acre) crater area that a local landowner sold to Korean investors. The Filipino landowner has land titles dating back to the Spanish colonial era, he said.

Manimtim said the project would generate jobs and bring benefits to his small town, which has spent much money evacuating residents in past Taal eruptions.

"When the volcano erupts, we move people to evacuation centers and spend for it," Manimtim told DZBB radio. "When the volcano is quiet, we think we should earn some money from it in return."

Philippine tourism authorities have spent money establishing trails used by tourists to hike to the volcano's crater lake. Filipino businesses, however, were reluctant to invest in an active volcano, he said.

The Korean investors think the spa would lure many of their compatriots who believe that stepping onto a restive volcano would bring good luck, Manimtim said.

Hundreds of people live in a Talisay village on the small island where Taal is located, although the area has been declared a permanent danger zone by government volcanologists. The 311-meter (1,026-foot) volcano lies about 70 kilometers (43 miles) south of Manila.

Taal, one of the country's 22 active volcanoes, has occasionally triggered seismic activity and geysers, and erupted mildly in 1977, causing no casualties or damage. A strong eruption in 1965 killed about 200 people.