British Prime Minister Gordon Brown said Sunday that Israel's ground offensive in Gaza had created a "very dangerous moment" in the conflict and he called for increased efforts to secure a ceasefire.

"This is a very dangerous moment," Brown said in an interview with BBC television.

"I think everybody around the world is expressing grave concerns. What we've got to do almost immediately is to work harder than we've done for an immediate ceasefire."

He said: "I sense that the Arab powers are as worried as we are about the turn of events."

As Israel poured thousands of troops and scores of tanks into Gaza Sunday in a bid to end militant rocket attacks, Brown said assurances needed to be given to both the Israelis and Hamas to pave the way for a ceasefire.

He explained: "I can see the Gaza issues for the Palestinians — that they need humanitarian aid — but the Israelis must have some assurance that there are no rocket attacks coming into Israel.

"So first we need an immediate ceasefire"

"So first we need an immediate ceasefire, and that includes a stopping of the rockets into Israel. Secondly, we need some resolution of the problem over arms trafficking into Gaza and, thirdly, we need the borders and the crossings open and that will need some international solution."

Brown said the Arab powers had to unite to stop the supply of arms to Gaza and he said Egypt's assistance would be especially crucial in shutting the illegal tunnels used to channel weapons to the enclave.

"I think the key to this is that international powers are able to give guarantees about ending the tunnels, and that will require Egyptian action," Brown said.

"Stopping the supply of arms... will require the whole of the Arab League to be united on that."

He said: "What I believe has got to happen over the next few days is that we have got to work with them and of course with the United States and the European Union, and (French) President (Nicolas) Sarkozy is visiting the region tomorrow."

A European Union ministerial delegation led by the new Czech presidency was visiting the Middle East on Sunday.