Baghdad (CNN) -- Bombs blew up at Sunni mosques in Iraq amid Friday prayers and at a restaurant in a Shiite area, the latest flurry of attacks in a country seething with sectarian tension.
At least 14 people were killed and more than 80 wounded in several incidents in and near Baghdad, the nation's capital, police and health officials said.
An explosive planted at the al-Qubeisi mosque in southwestern Baghdad killed four worshipers and wounded 46, police said.
In the capital's northeastern region, four people were injured when a bomb blew up outside the al-Razaq mosque, and six were hurt when a roadside bomb exploded near the Malek al-Ashqar mosque. South of Baghdad, five people were wounded by roadside bombs targeting mosques in Babel province.
Shootings left three people dead in central Baghdad, health officials said.
Hours later, at least seven people were killed and 21 others were wounded, police said, when a car bomb exploded outside a popular restaurant in Baghdad's Sadr City, a predominantly Shiite district.
The uptick in violence has prompted fears among Iraqi leaders and international powers that the tensions between Sunnis and Shiites could escalate and bring a return of the full-blown sectarian war that raged last decade.
"The country is at a crossroads," said Martin Kobler, U.N. special representative in Iraq.
"It is the historical responsibility of all Iraqi leaders to assume leadership and take bold initiatives, such as sitting together and calling in one voice for immediate restoration of calm and for a broad-based national dialogue."
He echoed the concern of Prime Minister Nuri al-Maliki, who said Thursday that "everyone will lose if civil war breaks out."
Protesters: 'Down, down with al-Maliki'
Since December, tens of thousands of Sunni demonstrators have taken to the streets, demanding that the Shiite-led government stop what they call second-class treatment of Iraq's Sunni community.
Sunnis, who had a lot of clout during the Saddam Hussein era, became a disaffected minority after his overthrow last decade. Sunni discontent contributed to years of bloody insurgent and sectarian violence in the country, where Shiites -- who represent a majority -- now hold sway.
Sunni anger exploded this week over security force actions in the Kirkuk province city of Hawija this week that led to deaths. Kobler appealed to the Iraqi government to conduct a thorough investigation.
Over the past few days, more than 100 people have been killed and hundreds of others wounded in clashes between Iraqi security forces and Sunni tribes in northern Iraqi provinces, including Salaheddin, Nineveh and Kirkuk.
In one town, Sulaiman Pek, government officials and religious and tribal leaders forged a peace deal. Dozens were killed and wounded there in recent days.
Ali Hashim, a Salaheddin provincial council member, said Friday that tribal leaders ordered their people to lay down their arms and let soldiers enter the city.
A lot of the anger is focused on al-Maliki, who is Shiite.
Tens of thousands of Sunni protesters in Falluja, in the largely Sunni Anbar province, aired their ire at the government Friday.
They say the al-Maliki government is controlled by the Iranian government. Some called for al-Maliki's removal and burned down an Iranian flag with an image of its president, Mahmoud Ahmadinejad, and al-Maliki, a CNN stringer reported.
One imam at the demonstration said that if politicians don't topple the prime minister, people would have to take their fight to Baghdad. The imam, Ali al-Bassri, called on tribal leaders to start an army to defend Sunni demonstrators and demanded the withdrawal of government security forces from the province.
"God is great," protesters shouted. "Down, down with al-Maliki."