By SARAH EL DEEB Darfur's most powerful rebel group and the Sudanese government on Tuesday signed a truce agreement after a year of internationally sponsored negotiations, raising hopes the bloody seven-year conflict could draw to a close.Rebel leader Khalil Ibrahim of the Justice and Equality Movement announced the cease-fire would begin that night as the international sponsors of the talks announced a $1.5 billion development fund for the war ravaged region.The once bitter enemies, Ibrahim and Sudanese President Omar al-Bashir, shook hands and embraced after the signing.The next challenge for the mediators will be getting the dozens of other rebel splinter groups to join the process as the arduous power and wealth-sharing talks begin.