The United States' top diplomat is expressing renewed concern at the Egyptian military-backed government's expanded crackdown on the Muslim Brotherhood.
Police rounded up dozens of Brotherhood members Thursday after the government declared the group a terrorist organization and announced stiff new restrictions on those who support it.
The interim government has blamed the Islamist group for a wave of violence, including Tuesday's car bombing at a police headquarters in the Nile delta town of Mansoura that killed 15 people.
U.S. Secretary of State John Kerry condemned that attack, as well as a Thursday bus bombing in Cairo that wounded five people. However, he also told his Egyptian counterpart Nabil Fahmy in a phone call that he is concerned about the group being designated as a terrorist organization and the recent detentions and arrests.
The State Department said Kerry "underscored the need for an inclusive political process across the political spectrum that respects the fundamental human rights of all Egyptians in order to achieve political stability and democratic change."
The Brotherhood denies involvement in the attacks, some of which have been claimed by Ansar Beit al-Maqdis, a hardline Islamist group. It says it is committed to peacefully restoring Islamist President Mohamed Morsi, who was ousted by the military following mass protests in July.
Kerry has in recent months said the ouster of Morsi, Egypt's first democratically elected president, was necessary to restore democracy. However, he has also criticized the widening campaign against the Brotherhood, the country's largest and most organized political group.
Over 1,000 people, mainly Islamist supports of Morsi, have been killed in the crackdown. Thousands more members of the Brotherhood, including most of its top leaders, leaders have been arrested.
On Thursday, the Egyptian Interior Ministry said a five year prison sentence will be given to anyone who joins a Muslim Brotherhood march, promotes the group verbally or in writing, or is caught with its publications or recordings.
The moves seem to have done little to stop the near-daily protests calling for Morsi's reinstatement. Late Thursday, Egyptian officials said one person was killed in the Nasr City district of Cairo during clashes between supporters and opponents of Morsi.
Meanwhile, state media say authorities arrested 16 Brotherhood activists Thursday in the Nile delta province of Sharkiya on suspicion of promoting the group's ideology, distributing leaflets, and inciting violence against the army and police.
At least 18 others were arrested or detained across the country for belonging to the group.
The unrest comes ahead of a referendum next month on a new constitution that is billed by the military as part of a democratic transition ahead of elections for a new parliament and president.