JUBA, Sudan (Reuters) - South Sudans polling centres closed their doors on Saturday after a week-long vote on independence from the north that could end a vicious cycle of civil war with the creation of the worlds newest state. Former President Jimmy Carter, leading a mission observing the vote, said turnout could reach 90 percent and that it seemed likely the south had voted for independence. Exhausted polling staff processed a straggle of voters on the final day in the southern capital Juba. Some officials were so tired they were sleeping behind their dusty stalls. I feel relieved as this is what weve been fighting for 21 years, said southerner Ayen Deng. Were waiting for the official results but we will be celebrating tonight. Final results are due before February 15 but could be announced as early as the beginning of next month. Of course there will be independence, we can smell it, said Santino Riek. The vote caps a 2005 peace agreement that ended decades of civil war between the mostly Muslim north and the south, where most follow Christianity and traditional beliefs. Northern officials have appeared increasingly resigned to losing the oil-producing south - which makes up a quarter of the countrys land - allaying fears conflict could reignite. Carter, leading one of the largest observation missions, told reporters in Khartoum a handful of centres had reported 100 percent turnout and were already tallying the results. We already know that in the south theres been about an average of 90 percent (participation) from the stations weve observed and I think they are representative, Carter said. In the few centres where he had seen counting under way, he said, the votes were practically unanimous in favor of separation with only a few ballots to the contrary. Its highly likely that the referendum result will be in favor of separation, Carter said, but added that no one should prejudge the outcome. At least 60 percent of registered voters needed to take part for the result to be binding. That point was reached just four days into the vote, according to the organizing commission. Carter also said the vote had probably met international standards and Khartoum said it would recognize the result, meaning all southerners must do now is wait to celebrate their independence day, likely on July 9. The former US president played down threats of popular protests in the north following the vote. My hope is that the opposition parties in the north will be brought into consultations with President (Omar Hassan al-) Bashirs party and that they will prepare for modifications for the constitution, he said. Students clashed with police in Khartoum and two northern towns on Wednesday and Thursday in protests over rising prices, part of an economic crisis that has been exacerbated by fears of the impact of losing the south. Southern independence campaigners have described the vote as a chance to throw off decades of perceived northern repression. Bashir said in a speech in Khartoum state that neither the north nor Muslims had ever oppressed the south, but rather the divisions were the legacy of the ex-colonial power, Britain. The south has been a burden on Sudan from independence until today, he said on state television. More than 182,000 exiled southerners have returned to the south since the end of October, according to UN figures, many of them fearing repercussions in the north after the vote. South Sudans government believes that figure could rise to as much as half a million by the beginning of July, said the UNs deputy humanitarian coordinator in Sudan, Lise Grande. Services are already overstretched. With more people coming back there will be tremendous pressures on agencies, she said.