Israeli Prime Minister Ariel Sharon has warned that his nation must withdraw from the Gaza Strip and parts of the West Bank if it wants to preserve its Jewish and democratic character.

His warning came as armed Palestinians on Friday abducted the Gaza police chief, and held him for several hours, in what observers believe is part of a power struggle between factions ahead of an Israeli withdrawal.

Mr. Sharon says Israel must not, "ignore the demographics. "

It is impossible, he says, to maintain a Jewish and democratic country, while ruling over millions of Palestinians in the West Bank and Gaza Strip.

This is believed to be the first time that the prime minister has stressed population as a reason for Israel to withdraw from Palestinian areas.

His warning came following several years of predictions by more liberal politicians that a high birthrate among Palestinians in the West Bank and Gaza Strip will mean that they will exceed the number of Jews living in Israel by the year 2010.

For this reason, a number of top Israeli Cabinet ministers believe that there should be a separation between the two communities.

Mr. Sharon made his comments in an address at a graduation ceremony at Israel's National Security College, where he spoke of the importance of his plan for Israel to disengage from the Palestinian areas.

Under the plan, Israel intends to dismantle all Jewish settlements in the Gaza Strip and four from the West Bank.

Mr. Sharon's Cabinet approved the plan in principle earlier this year, but dissenters resigned in protest and his coalition has lost its majority in the parliament.

On Sunday, the prime minister will begin talks with several parties, including the Labor Party, about possibly joining the government, with the aim of ensuring his disengagement plan is implemented.

Meanwhile, armed factions in the Gaza Strip are bidding for a share of power ahead of any Israeli withdrawal.

Some observers believe that the rivalry may have been behind Friday's abduction of Gaza's police chief, Ghazi al-Jabali.

He was kidnapped by armed Palestinians who surrounded his convoy on a Gaza coastal road. He was released several hours later.

An armed wing of Palestinian President, Yasser Arafat's Fatah faction claimed responsibility for seizing Mr. al-Jabali, who has been in charge of the police in Gaza for the past 10 years.