Human Rights Watch accused Egyptian authorities of gagging critics yesterday when border guards stopped its executive director and another US staffer from entering the country.

Executive director Kenneth Roth and Middle East and north Africa director Sarah Leah Whitson had been scheduled to launch a critical report by the group on mass killings by security forces last summer.

An airport official said the two had been turned back on instructions from a security agency after spending nearly 12 hours in Cairo International Airport.

It was the first time Egyptian authorities had stopped staffers from the New York-based group entering the country.

Human Rights Watch was to have released a report today about last year’s security crackdown on protesters backing deposed Islamist president Mohammed Morsi.

Mr Roth and Ms Whitson were there to brief diplomats and journalists on their report.

Hundreds were killed in one of the crackdowns, described by Human Rights Watch as the worst massacre in Egypt’s modern history.

It said Egypt’s police and army had “methodically opened fire with live ammunition,” killing at least 1,150 protesters during the dispersals of one of the largest sit-ins by Morsi protesters at Cairo’s Rabaah el-Adawiyah Square and five other demonstrations.

No-one has been held accountable for the crackdown and no formal investigation has ever been made public.

The group said it had shared its findings with the government but received no response.

“It appears the Egyptian government has no appetite to face up to the reality of these abuses, let alone hold those responsible to account,” said Mr Roth.

But Interior Ministry spokesman Hani Abdel-Latif retorted that Egypt’s National Council for Human Rights had conducted its own investigation.

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

Report author Omar Shakir said: “It seems the authorities have decided that only one narrative can be heard in Egypt.

“Shutting us down cannot erase what happened. We will continue to demand that those responsible be held accountable.”