LONDON - British officials were split over whether to expel an Israeli diplomat from London this week, with U.K. security officials viewing the move as overly harsh, Haaretz has learned.

But while the security officials, who are in regular contact with Israeli security officials stationed there, expressed reservations over the move, Foreign Office representatives supported it, a high-ranking official in the British Prime Minister's Office has confirmed.

The official said the Tuesday decision to expel the diplomat - identified in the British press as the Mossad security chief in London - was ultimately made unanimously, however.

The Foreign Office would not comment on the matter.

The expulsion was an extraordinary step taken after Britain found compelling evidence that Israel was responsible for the use of forged British passports in the plot to slay senior Hamas operative Mahmoud al-Mabhouh in Dubai.

A high-ranking Israeli diplomat said Britian was not overreacting.

"The British really did the minimum required on their part over the passports," he said.

Indeed, top Israeli and British officials held talks Wednesday over continuing intelligence sharing.

By contrast, intelligence cooperation between the two countries practically ground to a halt for nearly a decade after then-prime minister Margaret Thatcher ordered Mossad agent Arie Regev deported from the U.K. in 1988 over a double-agent operation in which the Israeli agency was believed to have spied on Britain.

This time, rather than stop sharing information, Britain will allow Israel to simply replace the diplomat with someone else.

"We gave the British everything they asked for on issues of Middle East terrorism that they deemed important," said a senior Israel Defense Forces official involved in intelligence sharing with Britain. "This was despite the fact that they didn't fulfill their commitment to change laws allowing the arrest of IDF officers in Britain on suspicion of war crimes."

The Foreign Ministry is considering forcing a British diplomat out of Israel in response to the Israeli diplomat's expulsion from Britain, Haaretz has learned.

But though advisers have encouraged Foreign Minister Avigdor Lieberman to take such a step, he has reportedly yet to decide on a response.

Meanwhile, Israeli officials are concerned Britain's decision could pave the way for other countries to expel Israeli diplomats as well.

The Australian reported yesterday that Israeli government sources told the Sydney-based paper that of the five countries whose passports were used in the assassination, Australia is the most likely to follow Britain's example.

Canberra summoned Israel's ambassador after the Dubai assassination in January, and Australian Prime Minister Kevin Rudd said he was not satisfied with Ambassador Yuval Rotem's explanations.

British Foreign Secretary David Miliband telephoned his Australian counterpart Stephen Smith yesterday to explain London's decision, The Australian reported.