Authorities in the Turkish city of Istanbul have banned an annual gay pride march planned for later this month, citing security and public order fears.

The ban, which was angrily denounced by the Istanbul pride organisers, came after ultra-nationalist and conservative groups said they would not allow "degenerates" to hold such events on Turkish soil.

The Istanbul governor's office said in a statement on Friday that the June 26 march had been banned out of concern for public order and safeguarding security.

The order means anyone taking part in the parade in defiance of the authorities risks facing intervention by the security forces.

READ MORE: Water cannon used to disperse Istanbul gay pride parade

In recent days, hardline groups had vowed to do "what is necessary" to stop Istanbul's gay pride march.

"Dear state officials, do not make us deal with these. Either you do what is needed or we will do it," Kursat Mican, Istanbul's head of Alperen Hearths, the youth group loyal to the far-nationalist Great Union Party, told reporters.  

Until 2015, the gay pride march had been held on 12 occasions largely without incident, growing into the largest such event in a Muslim country with thousands taking part in a celebration of diversity.

Last year, however, the parade was banned by the governorship hours before the event. Soon after, it was shut down through police intervention for the first time in its 13-year history.

'Flagrant violation'

The organisers of the march, in a statement on their Facebook page, denounced Friday's ban as a "flagrant violation of the constitution and the law".

They said that the event had until 2015 been held on the last Sunday of June every year since 2003 "to raise our voices against the violations experienced throughout the year and express our demands for equality, freedom and legal status".

The march's organisers also accused the governor's office of failing in its duty to protect the rights of citizens to exercise their rights and vowed to launch legal proceedings.

Activists are planning a week of events from this weekend culminating in a gay pride march on June 26 that traditionally follows Istanbul's famed shopping street Istiklal Caddesi and finishes in Taksim Square.

However, Turkey has been hit by a string of attacks this year, including a deadly suicide bombing on Istiklal itself that killed three Israelis and an Iranian and was blamed on armed groups.

Like last year, the march is also scheduled to take place during the holy Muslim fasting month of Ramadan.

Homosexuality has been legal in Turkey throughout the period of the modern republic and was also legalised in the Ottoman Empire from the mid-19th century.

But gays in Turkey regularly complain of harassment and abuse in a largely conservative Muslim society where open displays of same sex love are strongly frowned upon.

Gays in Turkey regularly complain of harassment and abuse in a largely conservative Muslim society [EPA]

Source: Al Jazeera and agencies