Malaysia has announced a further increase in security along its northern frontier, following the sharp upsurge in violence in southern Thailand.
By Jonathan Kent
Kota Bharu, Malaysia-Thailand border
Defence minister Zainal Abidin Zin said his government feared the violence might spill over the border.
Malaysia says it is determined to ensure that those responsible for Wednesday's attacks do not slip into its territory.
Police in the state of Kelantan held an emergency meeting about the situation.
Echoing the expressions of concern from Kuala Lumpur, the region's chief police officer told the BBC he was worried that Thailand's troubles could affect Malaysia.
He said that additional layers of security had been added along the border in a co-ordinated operation involving police and army units.
The real fear, though, must be that with more than 30 suspected rebels being gunned down in a mosque, opinion in predominantly Muslim Malaysia will be inflamed - and that the largely unspoken support for separatists in southern Thailand may grow.