By Alex Kirby BBC News Online environment correspondent

British Prime Minister Tony Blair has come in for some rough handling recently by environmentalists.

For a man who said his government would be the greenest ever, it must have been galling.

He will soon have a chance to prove his green credentials when he addresses the World Summit on Sustainable Development (WSSD) here.

Blair urged to invest more in clean energy

Not many campaigners are holding their breath in rapt expectation. A damning view of Mr Blair came on Sunday from Jonathon Porritt, chair of the UK's Sustainable Development Commission and a former head of Friends of the Earth-UK.

The prime minister, Mr Porrit said, showed "na�ve adulation" towards the business world. He had failed to provide green leadership.

The government's performance on domestic environment issues had been "deeply flawed" and "deplorable".

On transport his record is definitely a dull green

Paul Jefferiss

To give Mr Blair his due, Mr Porritt praised the UK's international efforts and compared it favourably with previous British administrations.

The word on the Johannesburg street is that Mr Porritt was largely right.

Paul Jefferiss is head of environmental policy at the UK's Royal Society for the Protection of Birds.

He told BBC News Online: "The government's record is patchy. On some issues, like energy, Mr Blair has worn a bright green badge.

"Even there, though, it's beginning to tarnish, as the early promise remains unfulfilled.

"On transport his record is definitely a dull green. He's made two quite promising speeches on the environment, but since then there's been a long silence"

Dubious on trade

Tom Bigg is a researcher at the London-based International Institute for Environment and Development.

He told BBC News Online: "The government's record in some areas is pretty positive.

"Things like building support for the Kyoto Protocol on climate change.

"It's much more dubious, though, on trade: its approach on the World Trade Organisation and the role of business is questionable at best.

"Whenever there's a clash, there's very little evidence of the UK choosing to uphold the environment over other interests."

Porritt: Blair must show he is serious

Andy Atkins is head of policy at Tearfund, a UK Christian relief and development agency.

He told BBC News Online: "The government is frightened to take hard decisions on issues of sustainable consumption such as our high dependence on fossil fuels and our addiction to unnecessary packaging on the products we buy."

This fear has its roots in the likely negative reaction from the British public when we are asked to change the way we live.

"Much greater investment in clean energy for domestic and industrial use, and measures to reduce our reliance on the car, are among the steps that could be taken by the government.

"What is needed is political courage from Mr Blair."

Ian Wilmore of Friends of the Earth, UK, still has hopes of the prime minister.

"Mr Blair talks the talk," he told BBC News Online, "He hasn't learnt to walk the walk yet.

The greens' verdict is that Tony Blair has not lived up to his early promise, but has a chance before the summit ends to rescue his reputation.