Riot policemen try to prevent protesters from marching to the presidential palace in Sanaa Feb 13, 2011. [Photo/Agencies]

SANAA, Yemen - Yemeni police clashed Sunday with anti-government protesters staging a third-consecutive day of demonstrations calling for political reforms and the resignation of President Ali Abdullah Saleh.

Several thousand protesters, many of them university students, tried to reach the central square in the capital of Sanaa, but were pushed back by police using truncheons.

The ouster of Egyptian President Hosni Mubarak after an 18-day uprising has emboldened protesters in Yemen and raised questions about the country's stability and other Western-allied governments in the region. Saleh has been in power for three decades and has tried to defuse the unrest by promising not to run again. His term ends in 2013.

Related readings:  Over 20,000 protesters in Yemen capital to oust president  Five-story building collapses in Yemen capital  WikiLeaks: Yemen nuclear material was unsecured  40 killed in car bomb in north Yemen

Witnesses said several protesters were injured and 23 were detained by police in Sunday's clashes. They said plainclothes policemen holding daggers and sticks also joined the security forces in driving the protesters back.

The protesters, chanting "people want to overthrow the regime", tried to reach Hada square in downtown.

Demonstrators tried to reach Tahrir Square, or Liberation Square, on Saturday, but security forces pushed them back. Buses ferried ruling party members, equipped with tents, food and water, to the city's main square to help prevent attempts by protesters to gather there.

On Sunday, local officials also provided Qat, leaves Yemenis chew as a stimulant, to plainclothes police and government supporters who spent their overnight in the square, witnesses said.

Police also set barbed wire around the square to prevent protesters from taking over the square.

The anti-government protests started Friday night as thousands of Yemenis took to the street to celebrate the resignation of Mubarak and demand the overthrow of their own president.