Seven people have been killed in Cairo in overnight clashes between security forces and supporters of Egypt’s ousted President Mohammed Morsi.
Police used tear gas to drive back protesters, some hurling rocks, who had blocked a main road in the capital.
The clashes came as a senior US envoy visited Egypt, saying it had been given a “second chance” at democracy.
William Burns met interim leaders but was snubbed by rival groups, including Mr Morsi’s Muslim Brotherhood.
Mr Morsi was ousted on 3 July in what many have said was a military coup. The army says it was fulfilling the demands of the people after mass anti-Morsi protests.
Monday’s battles erupted after hundreds of angry protesters blocked the 6 October bridge, a major arterial route.
Police fired tear gas to try to break up the blockade, and protesters responded by throwing stones. Other clashes broke out in the Giza district, at the south-west end.
The head of Egypt’s emergency services, Mohamed Sultan, said two people had died on or around the bridge and five in Giza.
State media said 261 people were injured in the clashes, which lasted into the early hours of Tuesday.
Mr Sultan said security personnel were among the casualties.
‘Get out, Sisi’
The latest clashes took place a week after more than 50 Morsi supporters were killed in fighting with troops outside the Republican Guard compound where the former president is believed to be being held.
The interim government has since announced its transition plan, under which a panel will be formed by next week to draw up amendments to the constitution and a timetable set for new elections.
But Morsi supporters are demanding his reinstatement and have been holding a round-the-clock vigil outside the Rabaa al-Adawiya mosque, in the east of the capital, and at Cairo University in Giza district.
Large crowds were again gathered there on Monday as Mr Burns, who is deputy secretary of state, visited.
“Get out, Sisi,” some shouted, referring to the head of the armed forces, General Abdel Fattah al-Sisi, who oversaw the overthrow of Mr Morsi.
Mr Burns met interim President Adly Mansour and Prime Minister Hazem al-Beblawi, as well as Gen al-Sisi.
He described the events of the last two weeks as a “second chance to realise the promise of the revolution” that ended the long, authoritarian presidency of Hosni Mubarak in 2011.
He called on the military to avoid “any politically motivated arrests”, saying the US remained committed to an Egypt that was “stable, democratic, inclusive and tolerant”.
But he insisted the US had “not come to lecture anyone. We will not try to impose our model on Egypt.”
The envoy’s comments come amid what correspondents say is an increasingly widespread antipathy towards the US among Egyptians on both sides of the political divide.
The US has stopped short of calling the army intervention a coup – doing so would trigger a legal stop of the some $1.5bn (£1bn) in the mostly military aid it sends to the country each year.
But is has called for Mr Morsi to be released.
William Burns: “Egyptians have second chance to put their post-revolutionary transition on a successful path”
Mr Burns said he planned to meet religious and civilian leaders, the heads of political parties and business figures during his two-day visit.
But both the ultra-conservative Salafi al-Nour party and the Tamarod anti-Morsi protest movement said they turned down invitations to meet Mr Burns, while the Muslim Brotherhood also said it had no plans to see him.
“Such kind of visit doesn’t mean anything for us because we believe that America supported this military coup,” Dina Zakaria, a member of the Brotherhood and its political wing the Freedom and Justice Party, told the BBC.
Islam Hammam, a Tamarod organiser, said the movement had turned down the invitation to talks with Mr Burns “because the United States did not stand with the Egyptian people from the beginning.”