Yemen was hit by fresh protests today after the arrest of a prominent female activist who had called for the ousting of President Ali Abdullah Saleh.

Inspired by the Tunisian revolt, thousands joined noisy protests in Sana'a last week, in the first large-scale public challenge to Saleh in his 32-year rule. Yemeni authorities responded with the arrest today of the activist Tawakul Karman, a key orchestrator of the demonstrations.

Karman, a member of the Islamist party Islah, was seized by plain-clothed police officers in the early hours of the morning on charges of organising unlicensed demonstrations.

"The arrest of a woman in the middle of the night is something very uncommon here and it's insulting to the people of Yemen," said Abdullah al-Faqih, professor of political science at Sana'a University. "If they don't release her soon she may become a figurehead like Mohamed Bouazizi [whose self-immolation inspired the Tunisian revolt]."

Khaled al-Ansi the general executive of Hood, The National Organisation for Defending Rights and Freedoms, was among a number of journalists arrested during the protest. Speaking before his arrest he said: "They arrested [Karman] because she's trying to transfer the Tunisian message to the Yemeni youth."

Outside Sana'a University, riot police armed with water-cannons used batons and shields to disperse protesters. A cameraman working for the satellite station al-Arabiya had his camera confiscated and was briefly detained for filming the skirmishes. Another cameraman working for al-Jazeera was beaten by police, the Qatar-based station said.

"The heavy security is evidence that Yemen has no democracy and freedom of expression. This is the last gasp of the regime," said Abdulkareem al-Khayati, 21, a student at Sana'a University.

Nasser Araybee, a Yemeni journalist for Cairo-based al-Ahram weekly said the protests, though small, were potentially dangerous for the government. "If there is no sign, or at least a pretence, of reform from the government then things will begin to escalate."

Yemen's 23 million citizens, among the poorest in the Arab world, have many grievances: the government is widely seen as corrupt and is abhorred for its association with the US in fighting al-Qaida. There are few political freedoms and the country is running out of water and oil reserves.

Faqih said: "The protests are significant but Yemen is a very different place from Tunisia: we have no middle class, a weak civil society and a president who relies on social not political ties. Many of his supporters will stay with him until the last day."

Early this month Yemen's parliament gave preliminary approval to a constitutional amendment eliminating presidential term limits, a measure that would allow Ali Abdullah Saleh to stay in power past the end of his mandate in 2013.