Switzerland has called on the Palestinian Authority to do more to fight against terrorist attacks following the latest suicide bombing in Tel Aviv.
The attack, the first since a ceasefire between Israel and the Palestinians was announced earlier this month, left four Israelis dead outside a nightclub on Friday night.
The Swiss foreign ministry condemned the attack which left more than 50 people injured. It also expressed its condolences to the victims’ families.
The ministry called on the Palestinians to bring those responsible swiftly before the courts.
On Saturday Palestinian police arrested at least two suspected militants in connection with the suicide bombing, acting on orders from Palestinian leader Mahmoud Abbas to track down those responsible for what he called an act of sabotage.
Palestinian security officials pointed to the Lebanese-based Hezbollah group, which has been trying to disrupt the informal truce, as the apparent mastermind of the attack.
Abbas hinted at Hezbollah involvement, holding a "third party" responsible for the bombing. But the group has denied responsibility.
Israel and the United States said Abbas had to act quickly and forcefully in order to rescue the fragile ceasefire.
The bomb went off as Israelis were waiting outside a seaside nightclub.
The bomber has been identified as a university student from a village near the West Bank town of Tulkarem. His parents said he was a devout Muslim, but had no history of militant activity.
The three main militant groups - Hamas, Islamic Jihad and the Al Aqsa Martyrs' Brigades – have denied involvement, and none hung the customary posters of congratulations at the bomber's home.
Since this month's Middle East summit, Israelis and Palestinians have stepped up security cooperation, and Israel has pledged to hand over security responsibilities in most of the West Bank to Palestinian forces.
swissinfo with agencies
It was the first suicide bombing in Israel since the death of long-time Palestinian leader Yasser Arafat on November 11.
The last such attack killed three people in a Tel Aviv market on November 1.
Palestinian president Mahmoud Abbas agreed a ceasefire with Israeli Prime Minister Ariel Sharon at a summit on February 8.
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