Israeli Prime Minister Benjamin Netanyahu and Defence Minister Israel Katz said the Israeli military had targeted and killed Beik, who they said had been involved in planning attacks and recruiting militants.
Hamas issued a statement confirming Beik's killing in the Israeli strike that medics said hit an apartment building in Gaza City's Nasr neighbourhood around dawn. Another person died from their wounds after the attack, health officials said.
Another strike killed a woman and wounded others in central Gaza's Nuseirat refugee camp.
Israel, which says Hamas has been rearming and launching attacks in violation of an October ceasefire, has stepped up strikes on the group in recent weeks.
The Israeli military says it has killed at least 20 Hamas figures this month, including some it identified as senior commanders or people who took part in the October 7, 2023 attacks or held Israeli hostages.
Hamas has denied trying to carry out attacks or rebuild its arsenal, and accuses Israel of undermining the Gaza deal.
Palestinian authorities say more than 73,000 people have been killed in Israel's assault on Gaza, launched after Hamas-led fighters killed about 1200 people in southern Israel in October 2023.
A US-brokered ceasefire agreed last year calls for the eventual reconstruction of the territory, but little progress has been made as negotiators have failed to agree terms for Hamas to disarm and Israel to withdraw its troops. Israeli air strikes have continued.
At least 1400 Palestinians, mostly civilians, have been killed in Gaza since the ceasefire took effect, according to the territory's health officials, while the Israeli military says four Israeli soldiers have been killed.
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