Bangkok - Thai police said on Friday a series of bombings that have killed four people and rattled tourist destinations in the south were acts of local sabotage and not "terrorist" in nature. "This is not a terrorist attack. It is just local sabotage that is restricted to limited areas and provinces," national police deputy spokesman Piyapan Pingmuang told reporters in Bangkok.At least 11 bombs, many of them twin blasts, have hit five southern provinces in the past 24 hours, killing four people and wounding several dozen, including foreigners."It is still unclear which group is behind the bombings," the spokesperson said, though he dismissed speculation that Muslim rebels waging a rebellion in Thailand's far south were behind the recent attacks. Thailand's southern tip has been home to a festering insurgency for over a decade, but the violence is largely contained to the border region, which lies far from the site of the recent bombings. A police statement ordered officers across the country to "step up security at significant government offices and symbolic places, especially the bus terminals, train stations, and airports, tourist spots, restaurants, and entertainment places where a lot of people are gathering".Local media have reported several fires in southern provinces over the past 24 hours but it was not immediately clear if they were connected to the bombings.