The father of the IDF soldier believed to have been captured by Palestinian militants in the Gaza Strip, hours after the start of a 72-hour humanitarian ceasefire, said he is confident the military forces will find his missing son.

2nd.-Lt. Hadar Goldin, a 23-year-old, Givati officer from Kfar Saba was abducted by Hamas during an operation to destroy cross-border tunnels used by the militants. Two other Israeli soldiers were reported to have been killed in the incident, which took place 90 minutes into a three-day truce.

The IDF reported that "a group of Hamas terrorists, including a suicide attacker, kidnapped 2nd Lt. Goldin at 9:30am and dragged him into a tunnel".

His father Simcha Goldin said that he is certain the IDF would "not leave any stone unturned" in their search for his son.

"The IDF (Israeli Defence Forces) will not stop until there's no stone left unturned in the Gaza Strip is and until Hadar is returned home safe and sound," he said.

"We want to support the Israeli army and the state of Israel in its fight against Hamas in Gaza and we are certain that the army will not stop under any circumstance, and will not leave any rock unturned in the Gaza Strip and will bring Hadar back home safe and sound," he said.

Both sides have accused each other of breaking the truce, which was announced by the US and the UN late on Thursday and began at 8am (6am UK time) Friday.

A Hamas official said the announcement of the soldier's capture was "a justification for Israel retreating from the truth and a cover-up for massacres".

Israel's Prime Minister Benjamin Netanyahu warned that Hamas and smaller militant groups will "bear the consequences of their actions".

US President Barack Obama called for the militants to free the soldier. He said he "unequivocally" condemned Hamas for capturing the soldier "minutes after a ceasefire had been announced".

UN Secretary General Ban Ki-moon, meanwhile, said he was "shocked and profoundly disappointed" by Hamas' violation of the truce.

The UK Foreign Office is also investigating reports that the missing Israeli soldier held British nationality. Britain's Foreign Secretary Philip Hammond said however, there is currently "no evidence" to suggest he has dual Israeli-British nationality.

The latest abduction is reminiscent of Hamas' capture of Israeli soldier Gilad Shalit in 2006. He was freed five years later in exchange for the release of more than 1,000 Palestinian prisoners.

Israel is stepping up its assault on Gaza following the reported abduction.

1500 people have now died in the latest conflict, most of them civilians. 8,400 have been injured, according to Gaza's health ministry.