"So far, no evidence whatsoever can be produced against the wrongdoers, whoever they are. The Council for National Security (CNS) seems to know best who they could be," said a source who asked not to be named.

The MPB are jointly investigating the bombs with the Crime Suppression Division. High-profile investigators from both police units and a number of bomb disposal teams made up a taskforce after yesterday's two-hour meeting.

Police are compiling file images from surveillance cameras installed near all eight bomb sites to scan for pictures indicating possible wrongdoers or other useful information. A number of uniformed officers at local police stations are interviewing witnesses who were near the scenes in the past 24 hours to gather more information.

The MPB investigators also dismissed the writing of "IRK" at three out of eight bomb sites - which suggested Muslim militants from the deep South played some part in the attacks - after interviewing witnesses and discovering that "IRK" was marked at several places across Bangkok well before the attacks.

The military said the IRK, while having nothing do with the Muslim insurgency in the South, was a new sign appearing for the first time in the wake of the bomb blasts.

Colonel Akkhara Thiproj, a spokesman with the Southern Border Provinces Peace-Building Command, said it was possible the IRK initials were a sign of a new politically-inspired terror group set-up to conduct operations in cities. Police expressed concern that the IRK initials could become popular and be painted by unruly teens to trigger fear and panic.

Meanwhile 17 victims, including two foreigners, remain in hospital. The Public Health Minister Dr Mongkol na Songkhla said yesterday the condition of many of the injured was improving. One patient was allowed to go home and Samrauy Seedow, the most seriously injured, could now breath without a respirator.

Several public figures visited victims at various hospitals including the Supreme Commander Gen Boonsang Niempradit, the Minister of Social Development and Human Security, and representatives of the Supreme Patriarch.

Relatives of the third dead victim Ekhachai Raungpoom yesterday picked up his body at Ramathi-bodi Hospital and held a funeral rite at Wat Dokmai in Yannawa.