Hezbollah said it had launched a volley of rockets at an Israeli aerial surveillance base on Tuesday in response to the Israeli military's deepest attack yet into Lebanese territory, with no immediate reports of casualties from the rockets.

Israeli warplanes struck the Bekaa Valley on Monday in an intensification of the cross-border hostilities that the war in Gaza triggered in October, prompting the Iran-backed group to respond with rocket fire on both Monday and Tuesday.

U.N. peacekeepers in Lebanon urged all parties to cease hostilities to avoid further escalation, warning that recent events could put a political solution to the conflict at risk.

The peacekeeping mission, UNIFIL, said it had seen a "concerning shift" in the exchanges of fire between Israel and Hezbollah and said it was engaging with parties to decrease tensions and prevent dangerous misunderstandings.

The base targeted by Hezbollah on Tuesday was the same one it has struck in previous attacks and there was no other sign so far of wider military retaliation by the group.

Israel said it had struck at Hezbollah air defences in the Bekaa on Monday in response to the downing of an Israeli drone that Hezbollah said it had shot down with a surface-to-air missile. The Israeli strike killed at least two Hezbollah members, Lebanese sources said.

Hezbollah then fired 60 rockets on Monday at an Israeli army station in the Israeli-occupied Golan Heights. The group did not say how many rockets were fired on Tuesday morning but said it was a "large volley".

Hezbollah politician Hassan Fadlallah said on Monday that Israel's strikes in the Bekaa "will not remain without response".

Israeli Defence Minister Yoav Gallant said on Sunday that Israel planned to increase attacks on Hezbollah in the event of a possible ceasefire in Gaza "until the full withdrawal of Hezbollah" from the border.

(Reporting by Maya Gebeily; Writing by Tala Ramadan and Angus McDowall; Editing by Kim Coghill and Miral Fahmy)