Police are investigating an incident on Saturday when a man drove a van at speed and almost knocked into policemen monitoring the Bersih 4 rally at Jalan Raja Uda in Butterworth.

Penang Police chief Datuk Abdul Rahim Hanafi said the incident occurred at about 10.30pm.

"We have not made any arrest but know the identity of the van driver and owner," he told reporters after an anti-crime operation in conjunction with the Merdeka Eve countdown here early today.

Some 500 police officers and personnel were involved in the operation in the state.

Abdul Rahim also said that Penang police had received seven reports on the Bersih 4 rally held at several venues in the state.

"Besides, police have also opened five investigation papers on the Bersih 4 rally," he added.

The Bersih 4 rally, which the police declared illegal, was organised by the electoral reform group Bersih 2.0 which said it was fighting for clean and fair elections, and a clean government, among other things.