Human Rights Watch said Tuesday an Israeli strike in south Lebanon that killed seven emergency workers was "an unlawful attack on civilians", urging Washington to suspend weapons sales to Israel.

The Israel-Lebanon border area has witnessed near-daily cross-border fire after Palestinian militant group Hamas's unprecedented October 7 attack on southern Israel sparked war in the Gaza Strip.

"An Israeli strike on an emergency and relief centre" in south Lebanon's Habariyeh on March 27 "killed seven emergency and relief volunteers" and "was an unlawful attack on civilians that failed to take all necessary precautions", HRW said in a statement.

"If the attack on civilians was carried out intentionally or recklessly, it should be investigated as an apparent war crime," it added.

Israel's military said at the time the target was "a military compound" and that the strike killed a "significant terrorist operative" from Jamaa Islamiya, a Lebanese group close to Hamas, and other "terrorists".

HRW said in the statement that it found "no evidence of a military target at the site", and said the Israeli strike "targeted a residential structure that housed the Emergency and Relief Corps of the Lebanese Succour Association, a nongovernmental humanitarian organisation".

Jamaa Islamiya later denied it was connected to the emergency responders, and the rescue group told AFP it had no affiliation with any Lebanese political organisation.

HRW said that "the Israeli military's admission" it had targeted the centre in Habariyeh indicated a "failure to take all feasible precautions to verify that the target was military and avoid loss of civilian life... making the strike unlawful".

The rights group said those killed were volunteers, adding that 18-year-old twin brothers were among the dead.

"Family members... the Lebanese Succour Association, and the civil defence all said that the seven men were civilians and not affiliated with any armed group," it added.

However, it noted that social media content suggested at least two of those killed "may have been supporters" of Jamaa Islamiya.

HRW said images of weapons parts found at the site included the remains of an Israeli bomb and remnants of a "guidance kit produced by the US-based Boeing Company".

"Israeli forces used a US weapon to conduct a strike that killed seven civilian relief workers in Lebanon who were merely doing their jobs," said Ramzi Kaiss, Lebanon researcher at HRW.

The rights group urged the United States to "immediately suspend arms sales and military assistance to Israel given evidence that the Israeli military is using US weapons unlawfully".