SANAA (Reuters) - Tens of thousands of supporters and opponents of Yemeni President Ali Abdullah Saleh held rival demonstrations in the capital on Friday and one person was killed in protests in the southern city of Aden, witnesses said. Protesters outside Sanaa University, demanding an end to Salehs 32-year rule, chanted slogans which have echoed round the Arab world since the uprisings in Egypt and Tunisia. The people demand the downfall of the regime, they shouted. About 4 km (2.5 miles) across town, loyalists shouted support for a leader they said was holding the fractured and impoverished tribal nation together. The creator of unity is in our hearts. We will not abandon him, they chanted. In Aden, one person was killed when more than 10,000 people took to the streets demanding Saleh step down. At least 25 people were wounded, mostly by live bullets, in the demonstrations that started after Friday prayers, witnesses said. One of the wounded was in critical condition. Eighteen people have been killed in the past nine days in a sustained wave of countrywide anti-Saleh protests galvanized by the fall of the Tunisian and Egyptian presidents. Saleh has said he will not give in to anarchy and killing. A US ally against the Yemen-based Al-Qaeda wing that has launched attacks at home and abroad, the Yemeni leader is struggling to end protests flaring across the Arabian Peninsulas poorest state. He is also trying to maintain a shaky truce with northern Shiite Muslim rebels and contain a secessionist insurgency in the south against northern rule. In the city of Taiz, 200 km (125 miles) south of the capital, about 10,000 people staged an anti-government protest. In Adens Mansoura district, protesters stormed a city council building and set fire to a government vehicle parked outside the building. Outside Sanaa university, Salehs opponents held an auction to raise money for their campaign, selling a car and a watch, which fetched 600,000 riyals ($3,000). The revolution has started. It will not stop until all of our demands are met, said Fouad Dahaba, an opposition member of parliament who attended the rally. We are not less than the people of Tunis and Egypt, who were emancipated. Saleh supporters in Tahrir Square in Sanaa, many of whom arrived in buses from provinces outside the capital, chanted Yes to stability, no to chaos. There is no use in trying to destroy the country and divide it. We all must enter a dialogue to preserve the national interest, said Mohammad Saleh.