US presidential hopeful John McCain says he understands Israel's response to rocket attacks by Palestinian militant groups.

Mr McCain was speaking in the Israeli town of Sderot, which has often been hit by rocket fire from the Gaza Strip.

"No nation in the world can be attacked without responding," he told reporters.

Mr McCain, a Republican senator who looks set to become the party's presidential candidate this autumn, also called for progress towards peace.

The Arizona senator, who is on a fact-finding trip to the Middle East, expressed sympathy for the people of Sderot.

"The fact is I come from a border state and if people were rocketing my state, I think that the citizens from my state would advocate a very vigorous response," he said.

Israel launched a military offensive in Hamas-controlled Gaza three weeks ago in response it said to Palestinian militant attacks.

More than 120 people were killed in the violence, most of them Palestinians.

Abbas call

The security situation along the border between Gaza and Israel lent urgency to US involvement in the Israeli-Palestinian peace process, said Mr McCain.

But he said he was not sure that a peace deal could be reached this year, despite the US administration's best efforts.

Mr McCain earlier had talks with Israeli Prime Minister Ehud Olmert and Foreign Minister Tzipi Livni.

After talks with Ms Livni, he reaffirmed his commitment to Israel and attacked the Islamist militant groups Hamas and Hezbollah.

"If Hamas and Hezbollah succeed here, they are going to succeed everywhere," Mr McCain told reporters.

Mr McCain also spoke on the telephone with Palestinian Authority President Mahmoud Abbas, afterwards telling the media that Mr Abbas "wants to get this [peace] process started".

He added that Mr Abbas did "not support the kind of activity that is taking place in Gaza" - a reference to the rocket attacks on southern Israel.

Mr McCain's tour of the Middle East and Europe includes meetings with UK Prime Minister Gordon Brown.

He will also visit France for talks with President Nicolas Sarkozy before heading back to the US.

Correspondents say Mr McCain's trip is good for his electoral prospects, because it will enable him to appear statesmanlike and presidential, while his potential Democratic opponents are still fighting for their party's nomination.