Yemenis commemorated dozens of people killed in weeks of street protests [Reuters]

Thousands of anti-government demonstrators have packed the streets of Sanaa, the capital of Yemen, to commemorate dozens of people killed in weeks of street protests.

The protesters turned out in 'Change Square' on Thursday to chant slogans against Ali Abdullah Saleh, the president, who withdrew an offer to step down by the end of the year as political talks collapsed.

Meanwhile, tribe members opposed to the embattled president attacked electricity pylons in the central province of Maarib, triggering power outages in parts of the capital.

The blackouts, lasting up to two hours, also hit the southern port of Aden and the Red Sea city of Hudeida.

A government official said the tribesman in Maarib had opened fire on the electricity towers.

One official accused tribe members "of the opposition party" of being behind the attacks. It was the second such incident in two weeks.

Mass protests have been shaking Yemen for weeks, with demonstrators inspired by successful uprisings in Egypt and Tunisia.

Opponents of Saleh's regime complain that the government has failed to meet the basic needs of the country's 23 million people.

Unemployment is about 35 per cent and 50 per cent for young people. Oil wealth is dwindling and water is running out.

Saleh, who has served for 32 years, has co-operated closely with the US in the battle against al-Qaeda's Yemen branch, which has used areas of the country that have long been out of state control to launch attacks.

The president is also battling regional rebellions in the north and south, with the opposition accusing him of exploiting Western fears that al-Qaeda could rise to fill a vacuum if he were ousted.

State control in Yemen has diminished sharply this month as the massive demonstrations continued to swell in major cities and the government pulled police from many towns.

In an attempt to arrange a peaceful transition, the head of Yemen's largest tribe, of which Saleh is a member, has guaranteed that the president would not be harmed if he steps down.

On Tuesday, Saleh held talks with Mohammed al-Yadoumi, head of the Islamist Islah party, once a partner in his government.

Saleh is looking for avenues to stay on as president while new parliamentary and presidential elections are organised by the end of the year, an opposition source said.

The talks have stalled and it was not clear how they could restart. Saudi Arabia has resisted Yemeni government efforts to involve them in mediation.

Source: Agencies