Pakistan's National Assembly elected its first woman speaker on Wednesday, a member of assassinated former prime minister Benazir Bhutto's Pakistan People's Party (PPP) which won elections last month.

Fehmida Mirza, 51, a medical doctor from a political family from Sindh province, easily defeated a candidate from the main party that backs President Pervez Musharraf by 249 votes to 70, said outgoing speaker Chaudhry Amir Hussain.

'It's a pleasure for me that this august house has elected a new speaker. She will be the first woman presiding officer of the assembly,' Hussain said before swearing in Mirza.

'Keeping in view her experience, I can say that she will be one of the best speakers,' he said.

Mirza's husband is a former PPP member of parliament and a close friend of Asif Ali Zardari, Bhutto's widower who became co-chairman of her party after she was killed in a suicide attack on December 27.

Mirza told reporters shortly before the vote she was honoured and humbled to become speaker.   'It is one thing to sit in opposition but this chair carries big responsibility. I am feeling that responsibility today and will, God willing, come up to expectations,' she said.

The PPP won the most seats in the February 18 elections but not enough to rule alone. It has agreed to form a coalition with the party of former prime minister Nawaz Sharif, which came second, and two smaller parties.

The former ruling party that backs Musharraf came a poor third in the election that was seen as a referendum on the unpopular president's rule.

Musharraf, an important US ally in its campaign against terrorism, is now faced with the prospect of inviting the election winners to form a coalition that could try to drive him from power.

Mirza won with a thumping majority of 249 votes in the 342-seat house, a show of strength by the winning parties and an indication they can command a two-thirds majority in the two-chamber parliament needed to amend the constitution.

The new government might seek to undermine Musharraf with changes to the constitution depriving the president of the power to dismiss a government.

A PPP official said the son of Bhutto and Zardari, Bilawal Bhutto Zardari, had arrived in Pakistan from Britain where he is studying and was expected to announce the party's candidate for prime minister in coming days.

The 19 year old was appointed chairman of the PPP after his mother's death but has said he will complete his studies at Oxford University before entering politics.

The lower house, meeting for its second session since members were sworn in on Monday, was also expected to elect PPP member of parliament Faisal Karim Kundi as deputy speaker.

Musharraf is expected to reconvene the National Assembly next week to elect a prime minister who will then form a government.-Reuters