The Soi Rang Nam grenade attack last night was meant for inciting trouble but remained unclear whether it was a politically-motivated incident, Deputy Prime Minister Suthep Thaugsuban said on Friday.
"From my point of view, the explosion was a disturbance but it was unclear about possible linkage to any political groups," he said.
Suthep said he received the iniital police report within 20 minutes after the explosion, which took place shortly before midnight near the King Power complex, seen as the liar of the Newin Chidchob faction of the Bhum Jai Thai Party.
One security guard sustained serious injuries after the grenade was lobbed into the guard box.
The deputy prime minister said he instructed police to beef up security in the capital in the face of upcoming local elections for city councillors on Sunday.