UNITED NATIONS - United Nations Secretary-General Antonio Guterres on Wednesday called for the full respect of the ceasefire agreed between Israel and militant groups led by the Islamic Resistance Movement (Hamas) on May 20.

Responding to a question about the secretary-general's reaction to Tuesday's escalating violence, Farhan Haq, deputy spokesman for the secretary-general, said at a regular press briefing that the secretary-general "expresses concern over the most recent round of violence."

Haq added that the secretary-general "would like to see the cessation of hostilities be maintained and solidified in order to give space for the relevant parties to work out arrangements to stabilize the situation."

Israeli army said on Wednesday that it had carried out the first airstrike in the Gaza Strip since a ceasefire ended its fighting with Gaza's ruler Hamas in May.

In the overnight attack, Israeli war jets struck military compounds belonging to Hamas in the city of Khan Yunis in the southern Gaza Strip, an Israeli military spokesperson said in a statement.

The statement accused Hamas of being responsible "for all events transpiring in the Gaza Strip" and warned that the group "will bear the consequences for its actions."

"The IDF (Israel Defense Forces) is prepared for any scenario, including a resumption of hostilities, in the face of continuing terror activities from the Gaza Strip," the statement read.

Hundreds of Israeli ultra-nationalists marched on Tuesday in East Jerusalem, waving Israeli flags. Some of them chanted "Death to Arabs" and other anti-Arab slurs.

Militants in Gaza responded to the march by launching "arson balloons" that caused at least 13 fires in southern Israel.