Five people, including one journalist, were injured in a clash between opponent "Red Shirt" and "Yellow Shirt" groups here on Tuesday.

The clash took place in front of the Crime Suppression Division offices on Phahon Yothin road. The rival protesters gathered after police summoned for questioning Manasnant Nookam, a female teacher, who publicly defamed a prominent Red Shirt supporter Darunee Kritbunyalai regarding a sensitive issue in Thailand in a luxurious shopping mall Siam Paragon in Bangkok last month.

The event was recorded as a 1.20 minutes clip and uploaded on YouTube, a video sharing website. It was widely shared among Thai Internet users.

Darunee, 63, then filed a defamation suit against Manasanant, accusing Manasnant of reviling her loudly, blaming her for alleged committing a serious crime, an action which Daranee said damaged her reputation.

Police summoned Manasnant for questioning but she did not appear on Tuesday and postponed her meeting with investigators to September 29.

The clash started as the pro-establishment Yellow Shirt supporters left the police compound after learning the meeting was postponed, they confronted a group of anti-establishment Red Shirts who followed the case outside the venue. Both sides pelted their rivals with salvos of rhetoric in a war of words, before the Yellow Shirts attacked a Red Shirt loudspeaker truck.

The clash resulted in five people injured, including both Red and Yellow supporters and one reporter. A Red Shirt pick-up truck was seriously damaged.

The protesters later dispersed in the afternoon after police commandos of the Crime Suppression Division intervened to control the situation.