The Muslim Brotherhood's political party will seek an inclusive majority in Egypt's parliament through alliances with rivals, its new chief said, addressing fears of a narrowly Islamist outcome to the uprising against autocratic rule.

The Freedom and Justice Party elected Saad al-Katatny, 61, as FJP leader on Friday, replacing Mohamed Morsy who has gone on to become the first elected president of Egypt.

Since the fall last year of strongman President Hosni Mubarak, Islamists have moved to the forefront of Egyptian politics thanks to organizational skills and finances unmatched by their liberal and leftist competitors.

But during the first post-Mubarak Parliament, dissolved by court order in June, liberal deputies sometimes walked out over what they saw as moves to ram through an Islamist legislative agenda without regard to Egypt's politically diverse society.

Speaking to Reuters in his first interview as FJP leader, Katatny pledged a broader political approach before the next parliamentary vote he said could take place around March 2013.

"Since the revolution, the FJP has worked to benefit everyone but there could have been more participation allowed to other parties before a decision was taken. This would have made everyone happy," Katatny said.

"At times, political forces complained not because of the decision but because they were not part of the decision-making process. We will set out to change this," the 61-year-old microbiologist said.

Katatny did not rule out a bloc with the ultraconservative Islamist Nour Party and liberal parties, but underlined that any alliance would be based on common policies, not ideology.

"The Freedom and Justice Party aims through an alliance with other political groups to achieve 50 plus one percent in the new assembly. But this time there will be a comprehensive programme that alliance members will draw up. This will ensure that once elected the majority bloc will work together inside parliament."

Katatny was the speaker of the first Parliament formed after Mubarak's overthrow, a short-lived assembly dominated by the FJP and ultraconservative Salafis.

Now the head of the 400,000-strong FJP must convince a wary public it can be trusted to govern fairly for all Egyptians.

Many Egyptians and rights groups are concerned that a new constitution being drawn up should not impose an Islamist vision of society out of keeping with Egypt's confessional complexity.

But the process has been hindered by a tug-of-war between Islamists, liberals and others in the 100-strong Constituent Assembly drawing up the document.

Now that the FJP has governing responsibility, many count on Katatny, who joined the Islamist movement in 1979, to transform it into a party less dependent on the Brotherhood's logistical, financial and political support, Brotherhood sources say.

"Until now the FJP's grassroots structure has not been as widespread or unified as the Muslim Brotherhood's grassroots base … so the party is constantly counting on the Brotherhood to rally big numbers during elections," said Katatny.

"The Brotherhood can within an hour rally huge numbers to public places. The FJP cannot do this yet. We want the Brotherhood to support the FJP but not interfere in its decision making process. This is possible."

In the previous Parliament, the FJP relied entirely on the Brotherhood for voter support, which led to Islamists securing around 70 percent of seats in the first Parliament.