The executive director of Human Rights Watch and another senior staff member have been denied entry to Egypt after being held at Cairo’s international airport for 12 hours.

Kenneth Roth, executive director of the New York-based rights group, and HRW Middle East director Sarah Leah Whitson were held overnight before being denied entry, Whitson wrote on Twitter.

“It’s official – shortest visit to Cairo ever – 12 hours before deportation for ‘security reasons’- the new Egypt certainly ‘transitioning’,” Whitson wrote.

The rights activists had flown to Cairo for the release of a report to mark a year since the mass killing of an estimated 700 opposition protesters by security forces, in one of the deadliest incidents of its kind in decades.

“We came to Egypt to release a serious report on a serious subject that deserves serious attention from the Egyptian government,” Roth said in a statement.

“Rab’a massacre numbers rank with Tiananmen and Andijan but Egypt gov’t wouldn’t let me in to present report on it,” he wrote on Twitter.

Interior Ministry spokesman Hani Abdel-Latif said he had no immediate response to the barring of the Human Rights Watch executives or the report.

However, he said Egypt’s National Council for Human Rights had conducted its own investigation into the dispersals.

“The Egyptian judiciary will have its say, and its decisions will be the ones to be implemented,” Abdel-Latif said.

Rights groups have warned of the sharp deterioration in human rights in Egypt since the overthrow of the country’s elected President Mohamed Morsi by the former army chief Abdel Fattah el-Sisi in July 2013.

Human Rights Watch’s European media director, Andrew Stroehlein, said it was the first time authorities in Egypt had denied entry to HRW staff, including under Hosni Mubarak, the deposed prime minister.

HRW said it had closed its office in Cairo in February because of concerns about the deteriorating security and political environment in the country.

Authorities have imposed extensive restrictions on civil society organizations over the past year, HRW said in a statement on its website.

Local groups in a joint statement have described the measure as a “declaration of war by the government on freedom of association and the work of civil society organizations in Egypt.” Al Jazeera