KHARTOUM – Police clashed with supporters of an independent electoral candidate in east Sudan on Thursday, arresting 31 people and injuring nine, opposition activists said on Friday. Political parties have repeatedly complained of harassment, vote-buying and intimidation by President Omar Hassan al-Bashir's National Congress Party (NCP) during the registration for the first multi-party elections in 24 years in April. The NCP denies any irregularities. "A very large number of police attacked them (my supporters) while they were still in their buses and injured nine people," said Hamed Mohamed Ali, who is vying for the post of governor of Red Sea state, rich in gold and with ports carrying handling vital oil exports. Ali is a disillusioned former member of the NCP. He said his supporters had not asked his or police permission for a rally in Port Sudan but had driven around town in buses on Tuesday beeping and shouting. "It was just like after a football match win," he said, adding the current governor and NCP candidate had used governmental cars and ambulances to call his supporters out for a march earlier on Tuesday without obstruction. The NCP denies using state resources for electioneering, which is forbidden by election law. Ali said the last of the 31 arrested had been released on Thursday. Nine were injured as police used tear gas and beat his supporters, he said.