Hague told Sky News television it was much more difficult to limit civilian casualties in a ground assault and it would threaten to prolong the conflict.

His comments came after Israeli Prime Minister Benjamin Netanyahu said the armed forces were ready to "significantly expand" their operation against militants in the Hamas-run Gaza Strip as it entered its fifth day.

Britain has said that Hamas bears the principal responsibility for the crisis over its rocket attacks on Israeli territory.

But Hague said it would be hard for the international community to maintain sympathy with Israel if it launched a ground operation.

"A ground invasion of Gaza would lose Israel a lot of the international support and sympathy that they have in this situation.

"It's much more difficult to restrict and avoid civilian casualties during a ground invasion and a large ground operation would threaten to prolong the conflict.

"We have made our views very clear on that with Israel, just as we have made very clear our view that the barrage of rockets from Gaza on to southern Israel is an intolerable situation for the Israelis and it's not surprising they have responded to that.

"A ground invasion is much more difficult for the international community to sympathise with or support -- including the United Kingdom."

Hague pointed the finger at Iran as a source of Hamas's weapons.

"Clearly a lot of weapons get into Gaza. Hundreds of rockets have been fired at Israel just in the last few days," he said.

"Iran is a country which we all suspect is prime mover behind that and supplies of such weaponry and attempts to supply other weaponry.

"There is Iranian involvement."

He said Britain would like to see an agreed ceasefire, with an end to the rocket attacks being an essential component of any peace deal.

"In the absence of that ceasefire, we of course are calling on all involved to deescalate, to avoid civilian casualties and to abide by international humanitarian law," he said.

Hague said it would be a "mistake" for the Palestinians to try to gain observer status at the United Nations at this point as it would be "divisive" with the United States -- the only power that can kick-start the peace process.

It could also lead to Israel cutting off revenues to the Palestinian Authority which could lead almost to its collapse, he said.