Britain unveiled its climate change bill on Tuesday, making it the first country to propose legally binding targets for cutting carbon dioxide emissions.

Environment Secretary David Miliband says the bill aims for a 60 per cent reduction of the greenhouse gas by 2050 and an interim reduction target of between 26 and 32 per cent by 2020.

And if the government fails to meet its targets — all compared to a 1990 baseline — it will initiate legal proceedings against itself.

Miliband told a news conference the bill marks "the first time any country has set itself legally-binding carbon targets. It is an environmental contract for future generations."

The draft also outlines plans for five-year "carbon budgets" capping CO2 levels, and a new independent body that would report to Parliament on Britain's progress in the fight against climate change.

The bill must be approved by both houses of Parliament to become law.

The government is calling the proposed law the world's first legal system for transition to a low carbon economy.

"We're bringing forward what I call a legislative framework for becoming a low carbon economy, a clean economy — a legislative framework that will bind all governments from 2008 till 2050," said Miliband.

Prime Minister Tony Blair says he hopes it will force other European nations, the United States, China and India to follow suit.

"China and India want to play a big part in this and we have to be encouraging them to do this. But they won't do it, obviously, unless America is a part of it, and vice versa is the case," said Blair.

'First step on a long journey'

Critics say the bill is a good start, but doesn't go far enough.

Friends of the Earth praised the proposal, but called for annual emissions reduction targets of three per cent.

Tony Juniper, the group's director, told the Guardian: "We are delighted that the government has recognised the need for a new law to tackle climate change.

"The U.K. will be the first country in the world to introduce a legal framework for reducing carbon emissions. But the draft bill must be strengthened if the U.K. is to set a global example."

Blair's government argues that annual targets are too rigid to make allowances for climate variations from year to year.

Andrew Pendleton, senior climate policy officer at the charity Christian Aid, also praised the bill but told Reuters that "if the final legislation is not significantly stronger, the process would represent a massive lost opportunity. It is the first step on a long journey."

Critics point out that despite the legally-binding aspect of the proposal, there are many examples of missed carbon targets, both at home and abroad. The Kyoto Protocol targets are supposed to be legally binding too, but many countries are not even close to achieving them.

Canada, for example, was one of the first countries to sign the Kyoto accord, with the previous Liberal government pledging to reduce greenhouse gas emissions to six per cent below 1990 levels.

In September 2006, Environment Minister Rona Ambrose said Canada had no chance of meeting its targets under the Kyoto Protocol.

While Stephen Harper's government has set targets similar to Britain's — the Conservatives have proposed emission cuts between 45 and 65 per cent by 2050 — Canada has proposed no hard caps on greenhouse gas emissions until 2020 at the earliest and the government has not promised to take itself to court should it miss its targets.

With files from the Associated Press