Israel and Hamas are to hold a five-hour ceasefire to allow UN humanitarian aid to enter the Gaza Strip.

The UN asked Israel on Wednesday for a unilateral pause, a UN official told Al Jazeera, as renewed air strikes on the enclave threatened a major humanitarian crisis.

The army said Israel has decided that "between 10am (7am GMT) and 3pm (12pm GMT) the Israeli military will cease operational activity within the Gaza Strip and hold its fire".

In a statement in response, Hamas spokesman Sami Abu Zuhri said: "The group agrees to a ceasefire for five hours".

At least 226 Palestinians have been killed and 1,685 others injured in nine days of bombardment by Israel on the Gaza Strip.

Hospitals in the city are running out of medical supplies and the Red Cross has warned of acute water shortages.

The renewed bombing came one day after a failed attempt at a ceasefire proposed by the Egyptian government. It asked Israel and Hamas to halt their fire on Tuesday morning and dispatch envoys to Cairo to discuss further terms.

The Israeli cabinet agreed, but Hamas, which said it was never consulted on the ceasefire, rejected it in "its current form".

The group has notified Egypt of the changes it was seeking, Ghazi Hamad, a senior Hamas official said.

"The initiative should include clear wording on fully lifting the blockade on Gaza, including opening all the crossings and releasing the rearrested prisoners from the [Gilad] Shalit deal in the West Bank," Hamad said.

Twitter campaign

Israeli jets resumed bombing the strip on Tuesday afternoon after a six-hour lull. Fighters in Gaza launched more than 60 rockets at Israel on Wednesday.

One Israeli was killed a by a Hamas-launched rocket on Tuesday, the only Israeli fatality since the fighting erupted on July 8.

Benjamin Netanyahu, the Israeli prime minister, had warned that Hamas will pay a high price for rejecting Egypt’s ceasefire plan.

On Wednesday, Netanyahu's twitter account used promoted tweets seeking to build support for the Gaza campaign.

Israel jets carried out dozens of air raids on Wednesday, targeting 30 houses, including those of senior Hamas leaders Mahmoud Zahar, Jamila Shanti, Fathi Hamas and Ismail Ashkar.

The army sent automated phone calls and text messages and dropped leaflets from planes threatening of more air strikes and prompting tens of thousands of residents to flee border areas.