The Egyptian government has severely restricted environmental groups' work, leaving activists fearful of publicly scrutinising authorities ahead of the country hosting a crucial global climate summit, Human Rights Watch said Monday.

The UN's annual Conference of the Parties (COP) involves nearly 200 countries, with hundreds of observers, NGOs and -- very often -- mass demonstrations designed to ramp up the pressure on political leaders to tackle climate change.

Egypt will host this year's event, COP27, in the Red Sea resort of Sharm el-Sheikh in November.

"The Egyptian government has imposed arbitrary funding, research, and registration obstacles that have debilitated local environmental groups, forcing some activists into exile and others to steer clear of important work," said Richard Pearshouse, environment director at Human Rights Watch.

"These restrictions violate the rights to freedom of assembly and association and threaten Egypt's ability to uphold its environmental and climate action commitments" as the host of COP27, the rights group added in a statement.

Egyptian authorities have lately championed concerns that industrialised countries -- the biggest polluters -- have fallen short in helping developing African nations tackle climate change impacts for which the continent shares little blame.

But for one environmentalist cited by HRW, this is "because this intersects with their interests, like the need for more funds".

HRW said it spoke to 13 activists, academics, scientists and journalists who have been involved in climate action in Egypt, who all spoke on condition of anonymity for security reasons.

Rights groups have repeatedly condemned Egypt's human rights record under President Abdel Fattah al-Sisi, who ousted Islamist president Mohamed Morsi in 2013 before becoming head of state the following year.

They allege the country holds some 60,000 political prisoners, many held on charges of "spreading false news".

HRW noted that interviewees pointed to a "recent expansion of official tolerance for environmental activities that are easily reconciled with government priorities".

But the rights group said that activists were fearful of drawing attention to issues including industrial pollution and the military's involvement in "destructive forms of quarrying", as well as major infrastructure projects.

Leading environmental organisations in Egypt "have been weakened severely by government restrictions and a pervasive sense of fear and uncertainty," HRW said, citing several insiders within such entities.