The demonstration coincided with a parliamentary vote that saw an overwhelming majority of lawmakers approve a package of constitutional amendments that lift the on-campus ban.

'Turkey is secular and will remain secular,' shouted the protestors, who packed a square in downtown Ankara, filling the main artery running through the heart of the city.

A majority of the demonstrators, who were waving the red and white star and crescent flag of Turkey and bearing portraits of modern Turkey's founder Mustafa Kemal Ataturk, were women, including some who wore headscarves.

Some were wearing headbands that read 'We are following your oath' along with pictures of Ataturk, who set up the republic in 1923 on the strict separation of state and religion.

Organisers did not give a figure for the protestors, but a police officer estimated that there were less than 100,000 people at the demonstration.

The protest was called by more than 70 trade unions and non-governmental organisations and dubbed the 'Rally for Secularism and Independence'.

It was the second large-scale demonstration against Prime Minister Recep Tayyip Erdogan's ruling Justice and Development Party (AKP), which tabled the reform package.

A similar demonstration last weekend drew 125,000 people.

'Tayyip, take your headscarf and stuff it,' said the demonstrators in Ankara.

'What is being done today in parliament is to eliminate the republican regime and replace it with bigotry. They want to destroy the secular democratic republic,' Mr Gokhan Gunaydin, from the organising committee, told the crowd.

Another organiser, Mr Tuncay Ozkan - the owner of a television network that broadcast the protest live - accused the government of treason.

'I am warning them, changing the constitutional regime is a crime. They should be tried for treason,' he said. 'We are here to defend the country.'

An elderly woman, wearing a headscarf with a red-and-white scarf around her neck, was among those that addressed the crowd.

'Long live the republic, damn sharia (law),' she said as she slipped her headcover back to reveal her hair. 'My hair is out in the open, I have nothing to be ashamed of.'

The AKP, which is largely distrusted by secularists for its roots in a banned Islamist party, says the headscarf ban violates freedom of conscience and the right to education.

For the secular camp, the headscarf is a symbol of defiance against the strict separation of state and religion.

They say lifting the ban will put social pressure on women to cover up and pave the way for a gradual lifting of a similar ban in high schools and government offices.

Leading academics have also warned that lifting the ban on headscarves would lead to clashes on campuses and a boycott of classes by some female academics.

The AKP says it is fully committed to secularism and has given assurances that the headscarf reform will only be extended to university students.

The ban on headscarves in universities was imposed after the 1980 military coup and has been implemented at varying degrees over the years, forcing many women to abandon their education and others to hide their headscarves under wigs to attend classes. -- AFP