The Queen has opened a Commonwealth¹ summit in Perth, amid tight security in the Australian city.

英国女皇在安保周密的澳大利亚城市珀斯宣布召开英联邦峰会。

The 54-nation organisation² - which represents some 2bn people around the globe - will discuss economic growth, climate change and human rights.

There will also be a debate on reforms to the British monarchy³ and to the way the Commonwealth is organised to give it greater influence on world events.

Most Commonwealth leaders are attending the two-day gathering⁴.

However, Indian Prime Minister Manmohan Singh has pulled out without giving a reason, according to the AFP news agency.

'Becoming irrelevant⁵'

Thousands of police have been deployed⁶ on the streets around the Perth Convention and Exhibition Centre ahead of the summit in the western Australian city.

The Commonwealth Heads of Government Meetings (CHOGM) are held every two years, and present an opportunity for developed and developing nations with current or former ties to Britain to discuss a range of issues.

But already other a number of divisive（区分的） subjects have come up at this year's gathering, the BBC's Duncan Kennedy in Perth reports.

They include the human rights record of Sri Lanka - which is due to host the next summit - and moves to get rid of laws in some member states which discriminate⁷（歧视，区别） against gay men and lesbians, our correspondent says.

He adds that there will also be discussions on proposals to change the laws of succession to the British throne, to give females heirs the same status as males.

And the leaders will discuss a 200-page report on reforms to the Commonwealth itself, including the appointment of a commissioner⁸ for human rights.

The report says the organisation is in danger of becoming irrelevant, unless it becomes more visible on the world stage and more pro-active in global affairs.