Oil producers from Opec and outside the group are finalising a plan to discuss freezing output at a meeting in Qatar in mid-April the latest move in a campaign by financially stricken crude exporters to shift the dynamics of an over-supplied market.

Qatar's oil minister said that countries would meet in the nation's capital Doha on April 17 without providing details of who would attend. The participation of Iran the only Opec member poised to increase supply significantly is seen as critical for the deal to re-balance the market but the meeting may go ahead without it according to two delegates who asked not to be identified because the talks are private.

Prices have rallied more than 30 per cent since a mid-February proposal by Saudi Arabia Russia Venezuela and Qatar to cap oil output and reduce a worldwide surplus that had seen prices slump to 12-year low in January. The summit in April would seek commitments from a wider range of producers both within and outside the Organisation of Petroleum Exporting Countries.

Kuwait was the first other Opec member to confirm it would attend according to an e-mailed statement from its oil minister.Saudi Oil Minister Ali Al Naimi and his Russian counterpart Alexander Novak who represent the world's largest exporters will discuss the meeting on Wednesday by phone one person said. Delegates from four Opec members said they hadn't yet received an invitation.

April 17 is the latest in a series of dates suggested for follow-up talks on the freeze. Nigerian Petroleum Minister Emmanuel Kachikwu said on March 3 that those talks would be held in Russia on March 20. The next day Russian Energy Minister Novak told state television channel Rossiya 24 that a meeting could take place between March 20 and April 1 in Russia Doha or Vienna.

The proposed freeze "put a floor under oil prices" Qatari Oil Minister Mohammad Al Sada said in an e-mailed statement on Wednesday. "To date around 15 Opec and non-Opec producers accounting for about 73 per cent of global oil output are supporting this initiative." - Bloomberg

Oil rallied after the Qatari statement gaining as much 2.2 per cent to $39.60 a barrel in London.

There are reasons to be doubtful that the planned freeze can radically alter an oil market that's fallen victim to a global fight for market share causing stockpiles to rise to a record high. Most significantly Iran is seeking to increase production after the end of economic sanctions and has said it won't participate in any accord until its output has recovered.

Iran boosted output by 187800 barrels a day to 3.13 million a day in February the biggest monthly gain since 1997 Opec said in its monthly report on Monday.

Brazil will also add more than 100000 barrels of supply this year and has shown little interest in taking part.

"We will now see if Opec and Russia are able to freeze the bears in the oil market" said Olivier Jakob managing director at consultants Petromatrix GmbH. "The significance of the agreement is that it could remove the perception that Opec is fighting for market share."

Other forces have driven prices higher in recent weeks. Outages from Iraq and Nigeria have disrupted more than 800000 barrels a day of supply and tightened the Brent market according to Citigroup. And falling drilling activity in the US shale industry has seen analysts raise forecasts for declines in North American production.

One key question is how fast shale production could come back if Opec and some non-Opec producers succeed in driving prices higher.

"It's not surprising they'd be willing to agree to this because the outlook for a further production increase was quite limited" Jeff Currie global head of commodities research at Goldman Sachs Group said in an interview on Bloomberg Television. "You can't operate a cartel the way you used to."