Presidential candidate Mahmoud Abbas (search) on Tuesday called Israel the "Zionist enemy," a marked escalation in his campaign rhetoric.

Abbas spoke to thousands of supporters after seven Palestinians were killed by an Israeli tank shell earlier in the day in the northern town of Beit Lahiya.

"We came to you today, while we are praying for the souls of the martyrs who were killed today by the shells of the Zionist enemy in Beit Lahiya," Abbas said during a campaign stop in the town of Khan Younis (search) in southern Gaza.

Abbas, the front-runner in Sunday's election for Palestinian Authority (search) president, is considered a moderate and has the tacit support of Israel and the United States. Abbas has criticized the armed Palestinian uprising and called for an end to violence.

However, in recent days Abbas has been campaigning in Palestinian areas that have been the hardest hit by four years of fighting, and has courted militants.

Held aloft by gunmen during campaign rallies, Abbas has indicated he prefers to co-opt the armed men, rather than crack down as Israel demands.

The recent campaign moves have caused some concern in Israel. However, Israeli officials have refrained from criticizing Abbas in public, apparently brushing aside some of his hard-line statements as campaign rhetoric.

An Israeli official, speaking on condition of anonymity, said that if Abbas is elected, "he will be judged by his actions, not his words, in providing security and fighting terrorism."