Supporters of ousted Egyptian President Mohamed Morsi continued to rally in Cairo, despite calls by the interim governments for protesters to leave two camps set up in the capital.
Witnesses on Thursday told Al Jazeera that military helicopters were hovering at low altitude over the sit-in at Cairo’s Rabaa al-Adawiya district, where demonstrators have been calling for the reinstatement of Morsi after his removal by the army on July 3.
In a statement on Thursday, the country's interior ministry urged protesters to leave the camps, offering "a safe exit" to those who heeded the call.
The ministry said those in Rabaa al-Adawiya and Nahda squares must "let reason and the national interest prevail, and to quickly leave".
On Wednesday night, the interim government ordered the army to take action against protesters. It said it authorised police to take "gradual steps" to break up the weeks-long rallies.
No specified date has been decided upon for clearing out the sit-ins.
Following the warning against the rallies, the US State Department urged Egypt to respect the right of peaceful assembly.
"We have continued to urge the interim government, officials and security forces, to respect the right of peaceful assembly," deputy spokeswoman Marie Harf told a news briefing. "That obviously includes sit-ins".
Germany's Guido Westerwelle, the first foreign minister to visit Egypt since Morsi was deposed, urged authorities to avoid "the appearance of selective justice".
"There is no justice of vengeance and no selective justice. There is law and it applies to everyone," he said on Thursday following talks with his counterpart Nabil Fahmy.
'Recipe for bloodshed'
Amnesty International said the decision to mandate security forces to end the pro-Morsi rallies is a "recipe for further bloodshed".
Follow our ongoing coverage of the political crisis in Egypt
"Given the Egyptian security forces' record of policing demonstrations with the routine use of excessive and unwarranted lethal force, this latest announcement gives a seal of approval to further abuse," said Hassiba Hadj Sahraoui, deputy director for the Middle East and North Africa at Amnesty.
More than 200 people have been killed in weeks of violence since the army deposed Morsi.
Earlier, authorities said they had referred the leader of the Muslim Brotherhood, Mohammed Badie, and two other senior movement officials to a court on charges of inciting violence.
US Republican senators John McCain and Lindsey Graham said on Wednesday that they would visit Egypt to help quell violence and press for elections.
Speaking to Al Jazeera, Amr Abd Elaty, an expert on US-Egypt relations at the Al Ahram Research Centre, said: "There is a political division between the US Senate and White House, and right now there is a lot of pressure on President Barack Obama because some senators feel that he did not preserve relations with liberals in Egypt.
"They think that he backed the Muslim Brotherhood, a group that many see as violent, oppressive and a threat to women’s rights."