Perth lockdown ahead of Commonwealth meeting

Police are out in force in central Perth for the start of the commonwealth leaders' meeting with the main business district in lockdown for the official opening.

Police choppers flew overhead early this morning as officers on motorcycles patrolled the main business thoroughfares, which have been closed to traffic.

Reports estimate around half of the state's 6000 officers are involved and about 800 extra police have been flown in from around Australia and New Zealand to assist in the security operation.

F/A-18 Hornet fighter jets have also been flying over the city.

Steel fencing lined St Georges and Adelaide Terraces ready for the motorcades carrying the Queen and dignitaries to the Commonwealth Heads of Government Meeting (CHOGM) venue at the Perth Convention and Exhibition Centre.

A big protest march is planned from 11am local time (4pm NZT) with demonstrators planning to stage a sit-on near the venue of CHOGM.

The Queen, who is staying at Government House on the locked-down St Georges Terrace, will officially open CHOGM at a ceremony starting at 10am.

More than 50 commonwealth leaders are in Perth for the three-day meeting.

CHOGM Action Network protest leaders say they do not intend to breach security zones during their protests but do want the right to get their messages across to CHOGM leaders.

They represent a variety of causes including anti-corporate greed, refugee rights, action on climate change and opposition to human rights abuses in some commonwealth countries.

An Occupy Perth movement is planning to occupy Forrest Place in the central city but WA Premier Colin Barnett, the city council and senior police say camping overnight will not be allowed.

Any attempt to move protesters on could lead to violent scenes as witnessed recently in similar Occupy protests in Melbourne and Sydney.

Police have been given special stop and search powers during CHOGM.

- AAP