Opec kept its medium and long-term forecasts for global oil demand relatively unchanged in a new report on Thursday, by also spotlighted the impact of environmental policies on the oil market.

By 2015, demand was expected to reach 91 million barrels per day (bpd), according to the cartel's 2010 World Oil Outlook, up from the 90.2 million bpd predicted in last year's report.

While recovery from the economic crisis had been faster than expected, pre-crisis demand levels from 2007 were unlikely to be seen until 2011, the Organisation of Petroleum Exporting Countries said.

By 2030, the cartel forecast demand at 105.5 million bpd.

In both the medium and long-term, most of that demand will occur in developing countries, it said.

"OECD (developed countries) oil demand falls slightly over the medium-term," and this was "also reflected in long-term projections," OPEC said in its report.

Meanwhile, "over the period 2009-2030, consumption in developing countries increases by more than 22 million bpd. Of the total global oil demand growth in the long-term, 75 percent is in developing Asia," the report said.

OPEC secretary-general Abdalla Salem El-Badri assured: "There are clearly enough resources to meet future demand."

However, climate change concerns and resulting environmental targets presented new challenges to oil producers, the cartel deplored.

"Legislation in some form or other is very likely to move ahead, with knock-on impacts for oil demand, probably oil supply, and almost certainly to refining."

The potential of such legislation "to reduce demand growth and further increase competition for product markets sends a clear signal that project developers will need to remain cautious about any investment decisions," OPEC warned, although it admitted that the issue of climate change was "pressing."

Poorer countries should not be the ones to pay for their richer partners' century-old emissions, the cartel also insisted.

In 20 years' time, and despite booming oil consumption in places like India and China, Annex I countries (Europe, North America, Japan, Australia and New Zealand) will still account for 64 per cent of all CO2 emissions since 1900, it noted.

"This underscores the need to fully reflect the historical responsibility in reaching an agreed outcome in the current climate change negotiations," OPEC said, calling for richer countries to make the biggest contribution towards fighting climate change, "given... their technological and financial capabilities."