Muslims around the world have celebrated Eid al-Fitr, the festival marking the end of the holy month of Ramadan, with prayer, reunions with family and friends, new clothes and sweet treats.

But the celebrations on Wednesday were overshadowed by the worsening humanitarian crisis in the Gaza Strip and Israel’s threatened ground offensive in the southernmost city of Rafah with no let-up in the six-month war.

In Istanbul, thousands of worshippers gathered at the Hagia Sofia mosque for morning Eid prayers, some carrying Palestinian flags and chanting slogans in support of people in Gaza.

In his holiday message, Turkish President Recep Tayyip Erdogan expressed support for Gaza, which he called a “bleeding wound on the conscience of humanity”.

“I hope that the Eid will lead to peace, tranquillity and wellbeing for our country, our nation, the Islamic world and all humanity,” he said.

The war in Gaza was also the focus of prayers at the Rahma mosque in the Kenyan capital, Nairobi.

“We should not forget our brothers and sisters in Palestine,” Imam Abdulrahman Musa said. “They have been subjected to unjustified aggression and a lot of violence (as) the world is watching in silence.”

In Indonesia, the world’s most populous Muslim nation, people joined communal prayers shoulder to shoulder on the streets and inside mosques. Jakarta’s Istiqlal Grand Mosque, the largest in Southeast Asia, was flooded with devotees offering morning prayers.

“This is the time for Muslims and non-Muslims to show humanitarian solidarity, because the conflict in Gaza is not a religious war, but a humanitarian problem,” said Jimly Asshiddiqie, who chairs the advisory board of the Indonesian Mosque Council.

Authorities in Pakistan deployed more than 100,000 police and paramilitary forces to maintain security at mosques and in markets.

As ethnic Malay Muslims performed prayers at mosques across Malaysia, Prime Minister Anwar Ibrahim called for unity and reconciliation in his message on the eve of Eid, saying no groups should be sidelined based on religion or any other reason.

“We must be firm, resolute and unwavering in our commitment to foster values and build a dignified nation,” he said. “However, let us not take this as a licence or opportunity to insult, undermine, or damage the cultural practices and way of life of others.”