The Foreign Ministry has stepped up its travel advisory to Bangkok and surrounding areas, prompting major travel agencies to suspend tours to the Thai capital until Tuesday, just ahead of Golden Week.

A day after deadly grenade attacks in central Bangkok, the Foreign Ministry on Friday raised its advisory by one notch to the second-lowest level on its four-grade scale, recommending that Japanese nationals "seriously consider" any travel plans to the affected region and "take sufficient safety precautions" if they decide to make a trip.

Travel agency JTB Corp. announced Saturday that it has suspended departures for tours to Bangkok until Tuesday, affecting 158 people with bookings. It will make a decision Monday whether to go ahead with departures on and after Wednesday. Tours to Phuket or other locations will not be affected, JTB said.

Nippon Travel Agency Co., another major tour operator, said it has suspended departures for tours to Bangkok from Saturday to Friday. However, KNT Co. said it will continue offering tours provided flights are operated normally.

JTB said 334 people on its tours are currently staying in Bangkok. The firm is planning to request that they move out of the Thai capital.

Meanwhile, Japanese companies' Thai subsidiaries suspended office operations in the main financial district of Bangkok on Friday.

The companies include Toyota Motor Corp., Nissan Motor Co., Hitachi Ltd., Canon Inc. and convenience chain operator FamilyMart Co.