Security forces have opened fire on demonstrators in south Yemen, injuring at least four.

Nouh al-Wafi, an activist, said several thousand protesters were rallying on Tuesday in the city of Taiz to demand the ouster of President Ali Abdullah Saleh when security forces fired on them.

Taiz has been a hotbed of two months of nationwide protests. Four protesters were killed in the southern city earlier this month.

The UN children's fund has said that 26 children have been killed during violent protests in Yemen over the last two months.

UNICEF spokeswoman Marixie Mercado said that most of the children killed in clashes between security forces and anti-government demonstrators died of wounds from live ammunition.

The UN Security Council will also discuss the crisis in Yemen for the first time on Tuesday.

"It is a sign of the growing attention that Yemen is attracting after Egypt, Tunisia and Libya," said a UN diplomat speaking on condition of anonymity, in reference to other protest-hit Arab states.

Also on Tuesday, a Yemeni government delegation is expected to leave for Abu Dhabi for talks with the six-nation Gulf Cooperation Council on its proposal for Saleh to transfer power to his deputy and end the crisis.

Opposition representatives held similar talks on Sunday in Saudi Arabia.

Meanwhile, Yemeni lawmakers who split from the ruling General People's Congress party have established a new political group calling for Saleh's ouster, a statement from the bloc said.

The new group, named "Justice and Building Bloc", comprises former ministers and members of the parliament who had deserted GPC in protest over the heavy-handed response by authorities to anti-Saleh demonstrations.

Members of the new group have called for "regime change" and the "immediate departure" of Saleh, according to the statement released late on Monday.

The bloc was announced in a ceremony on Monday in Sanaa.

It includes Nabil al-Faqih, former minister of tourism, Huda al-Baan, minister of human rights, and Khaled al-Wazir, transport minister, among others.