An Israeli military official on Monday rejected a one-day deadline imposed by Palestinian militants holding an Israeli soldier demanding that the Jewish state free Palestinian prisoners.

"We are studying the statement and for the moment are sticking to the official position expressed by the prime minister rejecting any negotiations with the kidnappers or giving into any blackmail," the official said.

Three Palestinian militant groups holding an Israeli soldier captive set the deadline earlier on Monday.

"Faced with the Zionist enemy's persistence in taking military measures and aggressions, we give it a delay expiring Tuesday, July 4 at 6.00 am (0300 GMT)," said a statement issued by the Popular Resistance Committees, the armed wing of the governing Hamas movement and the Army of Islam in Gaza.

"If the enemy does not meet the demands we laid out in our previous statement... we will consider the matter closed and the enemy will be responsible for all results," the statement added.

Spokesmen for Hamas's armed Ezzedine al-Qassam Brigades and the Popular Resistance Committees confirmed they had sent the statement.

On Saturday, the same three groups demanded the release of 1 000 Arab, Muslim, Palestinian and "other" prisoners but did not explicitly specify that the releases were conditions for securing the freedom of Corporal Gilad Shalit, who was seized eight days ago.

The three groups said all the detained leaders of Palestinian movements as well as elderly and sick detainees should be freed and reiterated an earlier demand for the release of women and juvenile prisoners from Israeli jails.

The statement also urged Israel to end its retaliatory military offensive in the Palestinian territories.

On June 26, the groups demanded the release of all Palestinian women and children from Israeli jails in exchange for information about the soldier, who was snatched in a deadly raid on an army post on June 25.

Israel has officially ruled out any question of negotiating with the abductors or releasing prisoners in exchange for Shalit's release.

On Monday, the army stepped up its offensive against the Gaza Strip, sending troops and tanks into the north, and carrying out a sixth night of air raids after Israel warned it would use all its power to free the serviceman.

AFP