Israeli authorities have arrested a man on suspicion of planting a bomb in a Tel Aviv bus that wounded 15 people hours before Israel agreed a ceasefire with Hamas in Gaza, police and security officials have said.

The unidentified Israeli citizen of Palestinian descent was detained on Wednesday night, officials said on Thursday.

Also arrested, police said, were a number of Palestinians allegedly affiliated with Hamas and Islamic Jihad militants in the Israeli-occupied West Bank on suspicion of having recruited the Israeli Arab to carry out the bombing.

"Members of this cell in Beit Lakya linked to Hamas and [Islamic] Jihad admitted during their interrogation having planned attacks against Israelis, prepared a bomb and chosen Tel Aviv as a target," a statement by Israel's security agency, Shin Bet said on Thursday.

Police spokesman Micky Rosenfeld did not give names or an exact number of how many people were in custody.

He said the Israeli Arab notified his Palestinian handlers in the West Bank when the bomb was in place on the commuter bus, and they then detonated the device with a mobile phone.

"The investigation is still under way, and other arrests are expected," the statement said.

Wednesday's bus bombing, the first serious bombing in Israel's commercial capital since 2006, had raised the possibility that Palestinians had entered in from the nearby West Bank to carry out the attack.

While Hamas rules Gaza, a fenced-off enclave under Israeli blockade, the US-backed Palestinian Authority governs in parts of the West Bank.

Earlier on Thursday, the Israeli army said that 55 suspected Palestinian militants had been arrested in the West Bank, citing a need to maintain calm after a truce ended the Gaza fighting.

Those arrested were termed "terrorist operatives", in an Israeli military statement.

This comes as Gaza and Israel enters its second day of an Egypt-brokered ceasefire which ends eight days of Israeli missile fire into Gaza and Hamas rocket fire into Israel which has seen 162 Palestinians killed and five Israeli's killed. 

Source: Agencies