Three Palestinian groups have called for the release of all Palestinian women and children from Israeli jails in exchange for information on a kidnapped soldier.
Corporal Gilad Shalit, 20, was snatched in a raid on an army post in the Gaza Strip yesterday. Two other Israeli soldiers and two Palestinian militants were killed during the attack.
The release demand was issued in the name of the Ezzedine al-Qassam Brigades, the armed wing of Hamas, the Popular Resistance Committees and the previously unknown Army of Islam faction.
The same three groups admitted carrying out Sunday's assault, which they said was to avenge the deaths of 22 Palestinian civilians killed in one alleged Israeli shelling and a series of air strikes.
It is understood 126 women and 300 people under the age of 18 are being detained out of a total of some 9,400 Palestinians in Israeli prisons.
Israel vows to free missing soldier
Palestinian President Mahmoud Abbas earlier held talks with Prime Minister Ismail Haniya of Hamas to discuss the issue.
The Israeli government said it woiuld hold the Hamas-led Palestinian government responsible if the missing soldier was harmed.
But a Hamas government spokesman said that the group's political leadership could not be held accountable.
The Israeli government has authorised 'all necessary measures' to ensure the return of the soldier.
Israeli Prime Minister Ehud Olmert said that he had put the army on standby for a major military operation against Palestinian militants.
Speaking in Jerusalem, he said: 'Let it be clear. We will reach everyone, no matter where they are, and they know it. There will not be immunity for anyone.'
The missing soldier also holds French citizenship.
A French embassy spokeswoman in Jerusalem has confirmed that the French government is also trying to help secure his release.