Downing Street is “appalled” by reports that Israel deliberately fired on peacekeepers in Lebanon.

The United Nations Interim Force in Lebanon (Unifil) has said an Israeli tank fired on its headquarters in the town of Naqoura in southern Lebanon on Thursday, hitting an observation tower and wounding two peacekeepers.

The peacekeeping force said its headquarters was affected by further explosions on Friday which injured two peacekeepers. One was taken to hospital.

Unifil also said several of its blast walls at a position in Labbouneh fell when an Israel Defence Forces (IDF) bulldozer hit the perimeter and tanks moved towards the UN position.

Unifil said this was a “serious development” and that “any deliberate attack on peacekeepers is a grave violation of international humanitarian law”.

A Downing Street spokeswoman asked about reports Israel had fired at Unifil forces said: “We were appalled to hear those reports and it is vital that peacekeepers and civilians are protected.

“As you know, we continue to call for an immediate ceasefire and an end to suffering and bloodshed. This is a reminder of the importance of us all renewing our diplomatic efforts.”

Asked if the Prime Minister sees this as a breach of international law, the spokeswoman said: “All parties must always do everything possible to protect civilians and comply with international law. But we continue to reiterate that and call for an immediate ceasefire.”

The Prime Minister later repeated his calls for de-escalation in the region when asked about the reports of Israeli attacks on UN positions.

He told broadcasters: “I’m very concerned about the situation in Lebanon, in Gaza, and the escalation more generally in relation to the conflict.

“So de-escalation, we have to find a political and diplomatic route forward here, and that’s why I’m working with allies and colleagues across the globe to ensure we get de-escalation of the situation.”

Asked whether that could involve further limiting arms exports to Israel, he said: “We’re working with our colleagues to de-escalate, that’s the immediate priority.”

The European Union’s top diplomat, Josep Borrell, said there was “no justification” for Israeli strikes that hit Unifil positions and called them “an inadmissible act”.

The Italian Defence Ministry summoned Israel’s ambassador in protest.

The Irish premier has said he is deeply concerned at the reports. The Irish Defence Forces are serving with Unifil amid heightened conflict in the region.

Taoiseach Simon Harris said all Irish troops in the south of Lebanon were accounted for.