The explosive was hurled around 6pm by the pillion rider on a motorcycle, and landed next to the protesters' barrier managed by the State Enterprises Workers’ Relation Confederation. Witnesses told police the motorcycle and the two riders fled in the direction of the Giant Swing located in front of Wat Suthat Thepwararam on Bamrung Mueang Road.
The injured men were identified as Narongchai Kornchantuak, 36, and Poramat Boonchan, 56. They were rushed to Bangkok Metropolitan Administration General Hospital. Mr Narongchai sustained lacerations on his left arm and his colleague suffered dizziness and chest pains from the explosion.
The confederation, comprising more than 40 state enterprise organisations and led by Somsak Kosaisuk, is an ally of the People's Democratic Reform Committee (PDRC) of Suthep Thaugsuban. It joined the PDRC anti-government and anti-Thaksin movement on Dec 1 last year, shortly after street rallies began.
The Erawan Centre said 736 people have been injured and 21 killed in political violence since the clash between pro- and anti-government followers at Ramkhamhaeng University on Nov 30 last year.