The European Union has struggled for both unity and influence in the face of the crisis that has engulfed the Middle East.

The 27-nation bloc has long been split between more pro-Palestinian members such as Ireland and Spain, and staunch backers of Israel including Germany and Austria.

But there has been less consensus on urging any halt to Israel's retaliatory bombardment of Gaza, which has killed over 6,500 people.

After days of negotiations, a draft statement for the summit calls "for continued, rapid, safe and unhindered humanitarian access and aid to reach those in need through all necessary measures including a humanitarian pause".

That statement -- which could change when leaders meet in Brussels -- falls short of demands from the United Nations for a "ceasefire".

Germany, wary of urging a more definitive halt that could tie Israel's hands, has mooted calls for humanitarian "windows" or "pauses" in the plural.

"Letters, commas, language matter, and that's how you find agreements," said a senior EU official.

But diplomats from some EU nations warn that delays over finding the right words as the death toll mounts are hitting the bloc's global standing and leaving it flailing in the face of developments.