In a statement, the SDP said it is being required by the police licensing office to hire 13 security personnel to help crowd control for the planned rally later this month.

"This condition which has just been recently imposed is completely unacceptable," SDP vice chairman Cheo Chai Chen said in a statement.

"First, this rally is a public event to address national issues such as the current recession. It is not an event for commercial or industrial purposes.

"As such, it is the government's duty to provide personnel for crowd control," the statement said. Hiring security guards would cost several thousand dollars, it added.

The party accused the government of "arbitrarily imposing conditions to make it increasingly difficult for the opposition to stage public rallies" adding "this strikes at the very heart of free speech in Singapore."

Last week, the party complained it was taking too long for the permit to be granted, noting the application was filed on July 18.

The police had imposed the same condition on civil rights group Think Centre when it organised a rally earlier this year to raise funds for veteran opposition politician J.B. Jeyaretnam, who was then threatened with bankruptcy charges.

Think Centre complied and hired its own security guards. It got a permit after seven weeks for the rally attended by at least 1000 people.

"At a time when the economy is in a severe recession and with the elections drawing near, it is crucial for the SDP to reach out to the electorate and communicate the party's alternative ideas and policies," the SDP statement said.

Approval for political rallies is rare in the strictly-governed city-state where the government has been accused of restricting freedom of speech.

The next general election is due by August 2002, but is widely expected to be held early.

Singapore politics have been dominated by the People's Action Party throughout the republic's 36-year history.

There are currently 89 government MPs and just two on the opposition benches, after Jeyaretnam was declared bankrupt.