Hundreds of Israeli tourists returned home on Wednesday after Israel issued an urgent travel warning its citizens to leave Egypt's Sinai Peninsula due to a kidnapping alert, police said.

The Counter-Terrorism Bureau issued a strongly worded statement late Tuesday, saying: "We call on all Israelis in Sinai to return to Israel immediately. Families of Israelis in Sinai are requested to contact them and inform them of this travel warning."

The head of the Counter-Terrorism Bureau in the Prime Minister's Office, Nitzan Nuriel, told Haaretz there was intelligence information about immediate plans to abduct an Israeli to Gaza. The organizations planning the abduction are thought to be working under Hamas instruction and funding, he said.

The peninsula, within driving distance of Israel, was once an extremely popular vacation destination for Israelis because of its inexpensive seaside resorts, nestled at the foot of desert mountains.

But a string of deadly suicide bombings in 2004 at several vacation spots popular with Israelis - including the Taba Hilton Hotel just across the Israeli border - has led many Israelis to shun the Sinai Peninsula, though the area still remains relatively popular.

Police spokesman Micky Rosenfeld said that about 650 Israelis were in Sinai when the warning was issued Tuesday - about half the number the initially estimated by counterterrorism officials. By midmorning Wednesday, some 430 had returned, Rosenfeld said.

Nuriel said this was probably the most serious alert in recent months. Egyptian security forces also launched an intensive effort to undermine the kidnapping, and sharply increased their contingents in popular Sinai resorts.

A year ago, 50 terror suspects with alleged Hezbollah ties were arrested in Sinai. The suspects were allegedly planning terror attacks on Israeli tourists.

Despite the bureau's earlier travel warning just before Passover, thousands of Israelis spent the holiday in Sinai. The Israel Airports Authority reported that departures to Sinai were up 36 per cent compared with last year. Another 69,000 people passed through the Taba crossing over Passover.

A source in the bureau said it was "regrettable that people ignore warnings and keep traveling to Sinai".

In Sinai, the owner of a beach and restaurant resort told Haaretz his business was packed with Israelis throughout the holiday. On Tuesday, an ordinary weekday, he had 10 Israeli couples staying at his resort.

"People heard about the new warning, but no one left," he said. "The Israelis don't listen to the warnings. They've been driven nuts for years now with alerts about how dangerous it is to come here."

"I asked them to call their families and calm them down, and tell them everything's alright. Friends from Israel called me and told me about the new warning, but I think it's unreasonable. If something were happening, we'd hear about it or feel it.

"We live in Sinai, the police are all over the place. It's a very safe place," he said.