The new standard aims to boost market confidence in the credibility of carbon offsets, but World Wildlife Fund (WWF) Canada has already said it cannot guarantee accredited projects will reduce greenhouse emissions.

The Voluntary Carbon Standard (VCS) was developed after a two-year consultation by not-for-profit groups The Climate Group and The International Emissions Trading Association (IETA) and industry association The World Business Council for Sustainable Development (WBCSD).

The Climate Group policy director Mark Kenber, co-chair of the VCS board, said it was an important step forward.

"The Voluntary Carbon Standard means business and consumer buyers can now trust the offsets they buy," he said.

"Its robust quality assurance will trigger a new global confidence in the voluntary market from corporate buyers, consumers and policy-makers."

But WWF Canada said the verification systems may be insufficient.

"WWF is concerned that bad offset projects will register under the VCS to make a quick buck," said Hans Verolme, director of WWF's Global Climate Change Program.

"If the VCS Board is serious about its standard they should screen its impact in a very transparent way and show they are ready to make improvements."

A joint statement from the three groups responsible for the VCS said the rules for certification were designed to strict ISO principles and are robust and transparent.

The carbon offsets market has been subject to criticism, with the global sustainability department of Melbourne's RMIT University releasing a report in May saying the carbon offset market "is a fragmented market, with little regulation and a variety of quality standards emerging internationally".

"It is difficult for offset purchasers to differentiate between a low-quality and high-quality offset, and it is often difficult for purchasers to be assured that their purchases of carbon offsets are in reality offsetting their emissions," the report continues.

The VCS board said market analysts estimate annual transactions in the voluntary carbon market could reach US$4 billion ($4.5 billion) in the next five years, with the new standard instrumental to this future growth.

Two recent carbon offset projects include Fiji Water's 'carbon negative' strategy and Woodside signing up to a $100 million carbon sequestration deal.