LONDON (Reuters) – British Prime Minister Tony Blair is expected to flesh out new plans on Friday to extend the government”s powers to deport or exclude foreigners who promote terrorism.

The proposals, which he has already outlined, will come one day after al Qaeda”s second-in-command Ayman al-Zawahri warned Britain and the United States of more attacks after two waves of bombings on London last month.

As part of a drive to crack down on so-called hate preachers, Home Secretary Charles Clarke is seeking to broaden existing powers to ban individuals he deems a threat to national security.

He wants to be able to exclude individuals who back terrorism or seek to provoke others to terrorist acts. In the past, courts have prevented the expulsion of people who have preached violence in Britain. Some other countries, notably France, can deport radical preachers more easily.

&#34It may be one of the hopes in this exercise that if the government sets out its criteria much more explicitly then if it goes to court to defend a decision, the judges may give it more respect,&#34 Labour MP John Denham told BBC radio.

Blair is set to give details of the plans, which do not require fresh legislation, at a news conference later.

Failed bombings on July 21 came two weeks after four suicide bombers killed 52 people in three underground trains and a bus. Police have linked the suicide bombers to al Qaeda.

In Thursday”s video aired by Al Jazeera television, Zawahri said Blair”s policies would bring more &#34destruction&#34 to London.

He warned Western nations they would not live in peace until they withdrew their troops from Iraq and other Muslim countries.

Britain plans to create new offences under security laws later in the year.

They cover &#34acts preparatory to terrorism,&#34 including financing or aiding attacks, glorifying or condoning terrorism and giving and receiving training in terrrorism.

Clarke also argues he needs his exclusion powers to be broadened out to include people who are deemed &#34not conducive to the public good.&#34

He has said he will draw up a list of &#34unacceptable behaviors&#34 including preaching, running Web sites or writing articles intended to incite or provoke terrorism.

Officials also plan to compile a database of individuals around the world who could be considered for exclusion and is working on deals with other countries, especially in North Africa, to enable courts to deport people seen as a menace.

As the police investigation into London”s attacks continues, two women charged under anti-terrorism laws for failing to give police information after the failed July 21 attacks on London will appear at London”s Bow Street Magistrates” Court later.

Yeshshiembet Girma, 28, and Muluemebet Girma, 21, of south London, were arrested on July 27 in an armed raid on a public housing estate in the Stockwell area of south London.