OPEC ministers in Vienna this weekend will debate whether the best policy is strict compliance with existing curbs or a new set of output cuts as they balance the issues of bulging oil stocks and a bruised world economy.

Ministers arriving ahead of Sunday's talks have said the first item on the agenda is tighter enforcement of agreements since September to lower supply targets by 4.2 million barrels per day (bpd).

But some of the 12-member group would favor going further by agreeing new output targets to drain down inventories as a weakened economy erodes energy use.

Kuwaiti Oil Minister Sheikh Ahmad al-Abdullah al-Sabah said further cuts would be easier for some governments than others because of their budgetary needs, state agency KUNA reported without quoting the minister directly.

So far the Organization of the Petroleum Exporting Countries has delivered about 80 percent of agreed cuts. It is estimated that 100 percent compliance would remove up to a further million bpd.

We need to discuss how to drain inventories. We need to evaluate demand and see if it is necessary to take additional measures, Venezuelan Minister of Energy and Petroleum Rafael Ramirez told reporters.

We have to analyze very carefully the economic situation world-wide ... It is worse than anybody thought it would be. We have a bad situation with demand, demand is destroyed.

Venezuela in the past has been among the first to ask for action to push up the oil price.

OPEC's biggest and most influential member Saudi Arabia has yet to comment publicly.

Sources said the kingdom, which has delivered the largest share of cuts so far, has emphasized the need for better output discipline from other members of the group.

HISTORIC CUTS

The cuts since last September are the deepest and most rapid yet and the rate of compliance is historically high.

They have helped to pull prices up from a low of $32.40 in December to around $46 now for U.S. crude -- a level that is just over $100 below last year's record high.

But inventories are still brimming and weak demand, especially heading into the second quarter when fuel consumption is typically at its lowest after the end of the northern hemisphere winter, could lead to further stock builds.

Washington-based PFC Energy said in a weekend briefing note OPEC's most likely course of action would be a new cut in formal targets.

OPEC will be mindful of the price crash in the late 1990s when oil fell toward $10 a barrel.

OPEC cuts then were implemented more slowly than this time round and prices did not stabilize for more than a year.

A difference between then and now is that fuel demand was only flat. This time it is predicted to decline by at least one million barrels per day this year compared with 2008 and the world economy is far weaker.

Another difference is that non-OPEC supplies are falling because of under-investment and the maturity of many oilfields.

That means any cooperation from non-OPEC countries with OPEC output cuts would be largely academic.

Some OPEC ministers have nevertheless called on the leading non-OPEC producer Russia to join in.

Moscow is sending a high-level delegation, including Deputy Prime Minister Igor Sechin and Energy Minister Sergei Shmatko, to attend Sunday's meeting as observers.

For related graphic, showing the relationship between OPEC output cuts and the oil price, please click on:

https://customers.reuters.com/d/graphics/OL_OPEV0309.gif

(Additional reporting by David Sheppard, Henrique Almeida, Alex Lawler and Simon Webb, Writing by Barbara Lewis; editing by William Hardy)

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