BEIRUT, Lebanon — An Israeli drone struck a Palestinian militia base in eastern Lebanon on Monday, Lebanon’s National News Agency said, the fourth time in three days that Israel has been accused of attacking Iranian-backed forces across the Middle East.

The string of events — only one of which Israel has claimed responsibility for — has heightened tensions and raised fears that what has so far remained a shadow war between Iran and Israel and their respective allies could escalate into a more direct conflict.

The strike on Monday hit the base of an Iranian-backed Palestinian militia, the Popular Front for the Liberation of Palestine-General Command, in the eastern Bekaa Valley. On Sunday, a drone exploded south of Beirut, shattering the windows of an office belonging to Hezbollah, another Iranian-backed group.

Lebanese politicians across the spectrum condemned the attacks and accused Israel of pushing the country toward conflict.