WASH INGTON (AFP) - Special envoy to the Middle East, George Mitchell, is resigning after two years in office, US officials said Friday, in a move likely to further complicate the moribund peace process. The surprise resignation by the seasoned diplomat comes only days ahead of President Barack Obama's highly-anticipated speech on the pro-democracy uprisings sweeping Arab nations on Thursday. The official announcement of Mitchell's departure would be made later Friday by the White House, officials said, stressing the Obama administration remained committed to striving to achieve peace in the Middle East. "The fact that this is a hard issue, an extraordinarily hard issue, is not news to anyone... who's ever attempted to work on it over these many years," said White House spokesman Jay Carney.