(Adds comments from Exxon, Chevron)

LONDON, June 1 (Reuters) - Europe’s top oil and gas companies urged governments around the world to introduce a pricing system for carbon emissions, as governments meet in Bonn, Germany, on Monday to work on a U.N. deal to fight climate change.

Criticised for not doing enough to tackle climate change, the chief executives of BG Group, BP, Eni , Royal Dutch Shell, Statoil and France’s Total said carbon pricing “would reduce uncertainty and encourage the most cost-effective ways of reducing carbon emissions widely.”

In a joint statement, the companies acknowledged “the current trend” in greenhouse gas emissions is too high to meet the United Nation’s target for limiting global warming by no more than 2 degrees.

“Our industry faces a challenge: we need to meet greater energy demand with less CO2. We are ready to meet that challenge and we are prepared to play our part,” the leaders of the six companies said.

“We firmly believe that carbon pricing will discourage high carbon options and reduce uncertainty that will help stimulate investments in the right low-carbon technologies and the right resources at the right pace.”

NOTABLE ABSENTEES

U.S. oil majors ExxonMobil and Chevron chose not to take part in the initiative, an industry source said.

Exxon said it was aware of the letter. Like Chevron, Exxon said it works with the International Petroleum Industry Environmental Conservation Association (IPIECA), a trade group, to develop a common position for climate change mitigation.

“It’s clear that there is a difference of views on each side of the Atlantic,” Patrick Pouyanne, Total’s Chief Executive, told reporters during a news briefing.

He said he and his counterparts from BP, Shell and Statoil had once met at a roundtable in Oslo and agreed on the European initiative.

“Instead of waiting for the smallest common denominator, we got convinced it was worth making a commitment as European oil majors, as we command a significant share of the oil market, without necessarily waiting for an American to come on board.”

Pouyanne said he was in talks with the two U.S. oil majors however and that he hoped that one of them would join the European initiative quickly.

In May, Ken Cohen, Exxon’s head of public policy, wrote a blog that said a “revenue-neutral carbon tax,” a scheme that shares similarities with carbon pricing, would be better at reducing greenhouse gas emissions than mandates.

The letter from the European companies was first published by the Financial Times on Sunday.

Climate Group, a non-profit advocacy, urged the world’s biggest economies to respond positively to the initiative.

“This is a symbolic moment, and demonstrates an important if not universal shift. It reflects a growing realisation within influential sectors of the fossil fuel industry of a need to adapt to both market and climate realities,” Mark Kenber, Climate Group chief executive, said in a statement.

Setting a price for each ton of carbon that emitters produce is meant to encourage companies to adopt cleaner technologies and shift away from using fossil fuels, primarily coal.

China is the world’s biggest carbon emitter.

The U.N. and World Bank have been strong advocates for policies that shift the responsibility to polluters to pay for carbon emissions.

“Business used to wait for governments for policy perfection, they are no longer waiting. They are moving forward, providing support and encouragement to national and international actions, because addressing climate change is their best policy for business continuity,” Christiana Figueres, head of the U.N. climate change secretariat, said at a carbon market event in Barcelona last week.

According to a report published by the World Bank last week 40 nations and over 20 cities, states and regions now have a price on carbon dioxide (CO2) emissions, covering around 12 percent of annual global greenhouse gas emissions, or the equivalent of nearly 7 billion tonnes of CO2.

The value of global schemes to price carbon, including trading schemes and taxes, totaled almost $50 billion as of April 1, the World Bank said.

Governments from more than 190 nations from June 1 to June 11 will work towards streamlining a draft text of a U.N. deal to fight climate change due to be agreed in Paris in December. (Additional reporting by Anna Driver in Houston, Ernest Scheyder in North Dakota, Michel Rose in Paris; Rishika Sadam in Bengaluru; editing by Terry Wade, Jason Neely, Louise Heavens and Bernard Orr)