In what is thought to be the first phone call between the two leaders in months, Netanyahu appealed for Abbas' help in locating the three youths, who went missing in the West Bank late last week.

"I expect you to help in the return of the kidnapped youngsters and in catching the abductors," a statement issued by Netanyahu's office quoted the prime minister as saying.

"The Hamas kidnappers went out from territory controlled by the Palestinian Authority and returned to territory controlled by the Palestinian Authority," Netanyahu added.

There was no immediate confirmation of the telephone conversation from the Palestinian side, but Abbas' office did issue a statement condemning both the kidnappings and a massive crackdown, which Israeli forces have been conducting as they search for those responsible.

"The Palestinian presidency condemns ... the kidnapping of three Israeli boys and the series of Israeli violations," the statement said. "The presidency reaffirms the importance of neither side resorting to violence," it added.

Germany also weighed in on the issue on Monday, calling for the release of the three Israeli youths.

"There are some indications that the three have been kidnapped. If this is the case, we condemn this action and urge those responsible to release them, free of harm, immediately," the Reuters news agency cited a German Foreign Ministry spokesman as saying.

Palestinian man killed

The statements came just hours after a 20-year-old Palestinian man was killed in clashes with Israeli soldiers who were conducting house-to-house searches in the Al-Jalazoun refugee camp near the West Bank town of Ramallah.

The Israeli military said that its soldiers had detained 40 Palestinians across the West Bank overnight, "including Hamas leadership and operatives," referring to the militant Islamist group regarded by Israel and others as a terrorist organization.

Witnesses said the speaker of the Palestinian parliament was among those arrested.

Netanyahu broke off peace talks with Abbas back in April after the Palestinian president announced that he was seeking to form a unity government made up of his Fatah party and Hamas.

pfd/kms (AP, dpa, Reuters, AFP)