Turkey’s President Recep Tayyip Erdogan has condemned Israel’s blockade and bombing of the besieged Gaza Strip, calling it a “massacre”.

Speaking to the members of his ruling AK Party in parliament on Wednesday, Erdogan said even war had a “morality” but the flare-up since the weekend had “very severely” violated that.

“Preventing people meeting their most fundamental needs and bombing housing where civilians live – in short, conducting a conflict using every sort of shameful method – is not a war, it’s a massacre,” he said, referring to Israel cutting off electricity and water to Gaza and destroying infrastructure.

“We openly oppose the killing of civilians on Israeli territories. Likewise, we can never accept the massacre of defenceless innocents in Gaza by indiscriminate, constant bombardments,” Erdogan said.

At least 1,055 Palestinians have been killed and thousands wounded in Israeli bombardments on Gaza since Saturday, when the Palestinian armed group Hamas launched an unprecedented raid inside Israel. At least 1,200 Israelis have also been killed and more than 100 taken hostage in the ongoing conflict.

Israel has put Gaza under “total siege” to stop food and fuel from reaching the enclave of 2.3 million people, many poor and dependent on aid. The Gaza administration on Wednesday said electricity went out after the only power station stopped working.

Erdogan said Israel’s repressive policies towards the Palestinians lay at the heart of the conflict. “Israel should not forget that if it acts like an organisation, not as a state, it will eventually come to be seen like one,” he said.

Erdogan criticised Israel’s “disproportionate” attacks on Gaza as “devoid of any ethical foundation”, and called on the world not to “blindly” take one side. Leaving the underlying issue unresolved would lead to new, more violent conflicts, he warned.

“We call on countries in the Americas, Europe, and other regions to take up a position between the parties that is fair, just, and based on humanitarian balances. Everyone should refrain from acts that will wholly punish the Palestinian people, like blocking humanitarian aid,” he said.

Turkey, which has backed Palestinians in the past and hosted members of Hamas, has been working to mend ties with Israel after years of animosity. Unlike the European Union and the United States, Turkey does not consider Hamas a “terrorist” organisation.

Ankara has offered to mediate in the ongoing conflict, with Erdogan and his foreign minister holding calls with regional powers, the US and others. However, Israel’s envoy to Ankara said it was too early to discuss mediation.