Jerusalem ? Israel took a step toward meeting a key Palestinian demand by agreeing Sunday to release some of the 5,000 prisoners it holds, but Prime Minister Ariel Sharon said the limited move would be conditioned on the Palestinians dismantling militant groups.

The release aims to strengthen the rule of Palestinian Prime Minister Mahmoud Abbas, who has vowed to carry out the U.S.-backed “road map” peace plan.

A top Palestinian official, however, expressed disappointment at the limited release. Radical groups, whose members are not slated for release, immediately condemned it.

The United States and Israel are strongly backing Abbas, also known as Abu Mazen, as an alternative to Yasser Arafat and as a Palestinian leader they believe can crack down on radical groups and help bring peace.

Sunday’s Cabinet decision excludes members of militant groups like Hamas and Islamic Jihad that oppose peace with Israel and excludes Palestinians who carried out or planned violent attacks against Israelis. Hamas, Islamic Jihad and Arafat’s Fatah movement are observing a cease-fire of at least three months.

Early today, Palestinian security officials said police arrested a woman who was planning a suicide attack against Israelis. They said she was in her 20s and was arrested after her parents reported to police that she had left behind a note about her plans. They said she was questioned and released into her parents’ custody while the investigation continued.

It was unclear how many prisoners Israel would release, but Sharon met earlier Sunday with Avi Dichter, head of the Shin Bet security service, who presented him with a list of several hundred prisoners slated for release. Israel’s Channel 2 TV said 400 would be released.