Sanaa, Yemen (CNN) -- Hundreds of anti-government protesters marched toward a presidential palace in Yemen on Sunday, calling for regime change in the Middle Eastern country.

Some of them chanted, "First Mubarak, now Ali," referring to Yemeni President Ali Abdullah Saleh and Hosni Mubarak, who recently resigned as president of Egypt after nearly 30 years in power.

Security forces put up a barbed wire barricade and blocked the protesters' path about two miles from the palace. At that point, the situation intensified as protesters turned away and attempted to reach the palace through side streets.

Clashes between protesters and police were reported by witnesses.

According to Tawakkol Karman, a prominent Yemeni rights activist and president of Women Journalists Without Chains, anti-riot police then "went into the crowd of protesters with batons and tasers," attempting to disperse them. Karman said she and other protesters were hit with sticks and that at least 12 people were arrested.

One of those arrested, human rights lawyer Khaled Al-Anesi, has since been released.

The CNN crew at the scene was surrounded by security officers, who seized the journalists' videotapes.

Nearby, a group of about 40 pro-government demonstrators chanted, "With our souls, with our blood, we will sacrifice for Ali."

The anti-government group first gathered at the gates of Sanaa University earlier Sunday, where another group of pro-government demonstrators carried pictures of Ali.

Police tried to disperse the crowds and stepped in to prevent pro-government demonstrators from following when the anti-government group headed away from the university and toward the palace.

The group of anti-government protesters included students and rights activists. Their numbers swelled from about 400 to more than 1,000 as they marched through Sanaa's streets.

The anti-government protests were significant because earlier in the day, Yemen's Embassy in Washington confirmed that the opposition coalition had announced its intention to hold a national dialogue with the administration. The government welcomed the opposition's willingness to initiate a dialogue -- though the protesters indicated otherwise.

Meanwhile, the state-run news agency Saba reported that Saleh had decided to delay a visit tot he United States that was to take place in late February.

Saleh has ruled Yemen for 32 years and has pledged not to stand for re-election when his current term -- which started in 2006 -- ends in 2013.

Mubarak's lengthy rule ended Friday when he stepped down after 18 days of anti-government protests rocked Egypt.

Echoes of Egypt's revolution resonated across the region, with anti-government protests in Yemen and Algeria. Demonstrations are also planned in Libya and Iran on Monday.

Brief clashes erupted Saturday in Yemen between hundreds of pro- and anti-government demonstrators who staged rival rallies in the capital.

The clashes, which left a small number of people injured, followed an anti-government protest Friday night in which men armed with knives attacked more than a thousand demonstrators, according to human rights groups.