China has reiterated plans to introduce a green tax for companies contributing to its growing pollution crisis.

A senior government spokesman said plans for an environment tax - first touted in December last year - were being pushed ahead and considered at a ministerial level.

"We are actively promoting this idea," said Pan Yue, deputy director of the State Environmental Protection Administration and a fierce campaigner for a greener China.

Speaking to reporters during the Chinese government's 17th Party Congress yesterday, he added that SEPA would "have to consult with relevant ministers" before any definite laws were introduced.

Yue, a globally recognised champion for environmental causes out of Shanghai, said he could not say how the tax would work or when it would be introduced.

Previous government suggestions about charging companies that generate high levels of pollution, chew through natural resources or are involved in unsustainable business practices have never included detail of how such a tax would operate.

However, it would almost certainly mean that US and European companies outsourcing their manufacturing activities to China would have to step up their environmental practices to avoid higher costs.

The pledge to look at tough new initiatives to reduce carbon emissions comes at an opportune time for China, as it faces increasing international pressure to clean up its act.

Meanwhile, an imminent Japanese report is due to reveal that carbon dioxide emissions in Asia will jump a massive 90 per cent to 5 billion tones by 2030.

The research by the Institute of Energy Economics Japan (IEEJ) is expected to show that China and India - the world's fastest growing and most heavily populated nations - will lead the increase with Chinese emissions set to climb 80 per cent and Indian emissions expected to soar 160 per cent over the period.

The paper, published by website Point Carbon ahead of the report's official release next Monday, also shows that China's primary energy consumption will soar by 3 per cent a year to 3.13 billion tonnes by 2030.

China is already the world's biggest energy consumer and polluter, with figures published in June revealing it had overtaken the US as the leading CO2 producer.