The Israeli attack on Hamas targets in Qatar is "unacceptable," German Chancellor Friedrich Merz and Foreign Minister Johann Wadephul said on Tuesday.

“Israel’s strike in Doha not only violates Qatar’s territorial sovereignty, but also jeopardizes all our efforts to secure the hostages’ release,” Wadephul said, noting that Qatar plays a crucial role in efforts to achieve a ceasefire and release the hostages.

The chancellor spoke by phone with Qatar's Emir Sheikh Tamim bin Hamad Al-Thani, a government spokesperson said.

Merz told the emir that the violation of Qatar’s sovereignty and territorial integrity by the Israeli attack is not acceptable.

"The war must not spread to the entire region."

Hamas said on Tuesday that five of its members had been killed in an Israeli attack in Doha, including the son of Hamas' exiled Gaza chief Khalil al-Hayya.