* Fossil fuel subsidies hampering green energy rollout

* More clarity needed on rules for carbon markets

* Calls echo Africa Climate Summit on faster action

LONDON, Sept 6 (Reuters) - Ditch fossil fuel subsidies, agree the rules for carbon markets and provide more finance to emerging markets.

That was the clear message from business leaders at the Reuters IMPACT conference in London on Wednesday about what they say needs to happen at the forthcoming COP28 climate summit.

The meeting of world leaders in Dubai beginning late November is seen as a crucial test of countries' willingness to accelerate action to limit global warming, with efforts so far doing little to stem global carbon emissions.

"The past summer again has proved in many parts of the world that there is a huge need for urgent actions among all stakeholders. Of course companies but also together with governments, regulators. We cannot afford to wait," said Peter Van der Poel, Managing Director at Ingka Investments.

While countries can agree a target, it is companies in the real economy which will determine whether the goal is met through their daily operations and investments, and to this end delegates called on policymakers to take bolder steps.

Many of the corporate delegates echoed calls from African leaders at the conclusion of a three-day Africa Climate Summit held in Nairobi this week for developed nations to do more to help provide finance to developing countries.

Anél Bosman, Group Managing Executive at Nedbank Corporate and Investment Banking, said the wider world's debate on the environment had at times sounded "tone deaf" to Africa, with more focus needed on the importance of social development.

Among the more contentious issues is how to handle the phase down of use of fossil fuels. Despite this, failure to remove fossil fuel subsidies would make it harder to expand renewable energy in some countries, Ingka's van der Poel said.

"It makes it more difficult and less transparent. And certainly for the bigger financing (into green energy) that needs to happen, it is an impediment."

Despite the phasing out of fossil fuels, and not least subsidies, being "the elephant in the room", Helena Viñes Fiestas, Chair of the European Union's Platform on Sustainable Finance, said she did not expect to see much progress at COP28.

"So my hope is that we progress on finance, particularly on adaptation, definitely on the deployment of low-carbon infrastructure and on the loss and damage fund that was promised," she said.

Developing the global market to generate, buy and sell carbon or biodiversity credits was also a key focus for African leaders as they look for ways to monetise their natural resources and better pair development with environmental goals.

While many corporates have been keen to buy credits and offset the emissions from their operations, the market for so-called voluntary carbon credits has yet to scale, with some put off by uncertainty around the quality of some credits.

"We want to be as credible as possible, and right now in the offsetting world it is very difficult to find the right instruments and the right offsets," said Preeti Srivastav, Group Sustainability Director at drinks company Asahi Europe & International.

Andy Griffiths, head of sustainable procurement at UK-listed Diageo, also called for "increased rigour and understanding so that businesses can align and invest effectively and with certainty as well."

Collectively, though, the world's efforts to reduce emissions were nowhere near where they need to be, something the Global Stocktake of efforts so far would highlight in Dubai, said Vines Fiestas.

"My concern is that we have very little hopes for that ambition to be raised during COP28," she said.

To view the live broadcast of the Road to COP Stage, go to the Reuters IMPACT news page:

(Additional reporting by Richa Naidu, William James and Helen Reid; Writing by Simon Jessop; Editing by Alexander Smith)