Police say at least 12 others were injured.

The accident followed heavy overnight rain at the site - one of Thailand's most sacred Buddhist temples, the Phra Pathom Pagoda in Nakhon Pathom province, west of Bangkok.

The three ceremonial metal columns, 24m-27m high, were filled with tons of joss sticks - thin, wooden sticks of incense which are burned during religious ceremonies.

The structures were built to commemorate the 84th anniversary of the construction of a Buddha image at the temple.

They were due to be lit on Monday night in front of thousands of devotees.

Illegal structures

Witnesses said they heard a noise before the columns fell on people who had been praying and making offerings at their base.

"I had just finished saying my prayers when I heard a noise and the joss sticks fell," one man said, adding that he narrowly escaped death.

Police Lieutenant Colonel Suraphong Phisuthiwong said the structures were built illegally in April but were not removed because they were part of a temple complex.