ISTANBUL, Turkey, (AP) -Tens of thousands of secular Turks gathered in Istanbul Sunday, chanting slogans against the pro-Islamic government that has faced severe criticism from the country’s powerful military.

It was the second large demonstration against the government in just two weeks and shows a deepening division between secular and Islamist camps in Turkish society. More than 300,000 secular Turks staged a similar rally in Ankara two weeks ago.

“Turkey is secular and will remain secular,” shouted thousands of flag-waving protesters, who traveled to Istanbul from across the country overnight.

The rally was organized more than a week ago but it came a day after Prime Minister Recep Tayyip Erdogan’s government rejected a stern warning from the military over the country’s disputed presidential election, calling its interference unacceptable in a democracy.

The ruling party candidate, Foreign Minister Abdullah Gul, failed to win a first-round victory Friday in a parliamentary vote marked by tensions between secularists and the pro-Islamic government. Most opposition legislators boycotted the vote and challenged its validity in the Constitutional Court.

The military, which has long guarded Turkey’s secular traditions, said Friday night it was gravely concerned and indicated it was willing to become more openly involved in the process — a statement some interpreted as an ultimatum to the government to rein in officials who promote Islamic initiatives.

Gul has promised to uphold the country’s secular traditions amid concerns that his victory will strengthen the role of Islam in politics.

The election has contributed to a sense of polarization in a country that has enjoyed relative economic and political stability for years and is seeking entry into the European Union. The EU has been pressing Turkey to curb the influence of its armed forces in politics.