By Alistair Thomson and Lamine Ghanmi
DAKAR, March 13 (Reuters) - Leaders of the world's biggest Muslim body opened talks on Thursday to tackle difficult issues from poverty to hostility toward Islam, but those goals were quickly overshadowed by a confrontation between Chad and Sudan.
Heads of state of the 57-nation Organisation of the Islamic Conference (OIC) -- the second largest inter-governmental bloc after the United Nations -- convened in the Senegalese capital Dakar for a two-day meeting to overhaul its unwieldy charter.
The meeting, however, started on a sour note as Chad accused its neighbour and fellow OIC member Sudan of launching a rebel attack across its border.
"The Chadian government informs national and international opinion that Sudan on Wednesday March 12, 2008 launched several heavily armed columns against Chad," an official statement released in the Chadian capital N'Djamena said.
It was a major embarrassment for Senegalese President Abdoulaye Wade who had billed the summit as the opportunity for a definitive peace deal between the two oil-producing states, after five previous agreements had collapsed.
A deal seemed unlikely after Sudanese President Omar Hassan al-Bashir failed to turn up to a meeting with Chadian leader Idriss Deby late on Wednesday, leaving U.N. Secretary-General Ban Ki-moon, called as witness, waiting for nearly three hours.
Efforts to review the OIC's 40-article charter also appeared to have run aground after foreign ministers broke off their discussions without agreement on Wednesday, despite having extended their two days of talks by an extra day.
Long criticised as being ineffective and bureaucratic, OIC officials hope a revision of the charter can assign the group a more active role in fighting poverty and Islamic militancy.
"It's up to the heads of state to make the decision," Wade told the opening ceremony of the summit. "We are on the point of adopting the charter and we hope this adoption will come today."
The charter discussions include calls for more aid from the OIC's richest members, like Saudi Arabia and Kuwait, to its poorest states, most of them in sub-Saharan Africa where radical groups like al Qaeda are attempting to gain a foothold.
A $10 billion fund for Islamic development set up by the organisation has so far received pledges for only $2.6 billion.
Another key change would allow the group to take decisions by a two-thirds majority, instead of requiring unanimity -- difficult to achieve in a large body with such cultural and political divisions, spanning Africa, Asia and the Middle East.
Some members are pushing to make OIC membership conditional on a state having a "majority" Muslim population, but this has been resisted by mixed-religion nations like Uganda.
Pakistan was also insisting the new charter should make potential members resolve their conflicts with existing members before being allowed to adhere -- reflecting its long-running dispute with neighbour India over the Kashmir region.
With several prominent leaders not present -- from Saudi Arabia's King Abdullah to Libya's Muammar Gaddafi and Pakistan's Pervez Musharraf -- some delegates had called for a decision on the charter to be postponed until a Cairo summit in three years.
The meeting, however, was due to throw its weight behind the democratic government in Iraq, denouncing terrorist threats.
"The decision has been taken, a good decision for Iraq, the OIC will open an office in Baghdad," Iraqi Foreign Minister Hoshiyar Zebari told reporters. (For full Reuters Africa coverage and to have your say on the top issues, visit: africa.reuters.com/ ) (Writing by Daniel Flynn; Editing by Pascal Fletcher and Mary Gabriel)