BAGHDAD -- Iraqi security forces recaptured a key bridge from Islamic State of Iraq and Syria (ISIS) militants in the capital of Anbar province on Friday, said an Iraqi security official, as the country's top Shiite cleric renewed calls for national unity among political rivals in the face of the Islamic militant threat.

Police colonel Mahdi Abbas said Iraqi security forces recaptured the al-Houz bridge over the Euphrates river after fierce clashes with ISIS militants in western Ramadi.

Abbas said that the bridge was controlled by ISIS for several months and served as a primary supply route for the insurgents.

The security situation in Ramadi sharply deteriorated after ISIS seized three villages around the city, forcing thousands to flee their homes. CBS News correspondent Holly Williams reported that ISIS also blew up a police station during the attack.

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The militants have been battling Iraqi forces around Ramadi for several months now, Williams reported, and large parts of the surrounding province of Anbar are already under ISIS' control. The area was a center of the al Qaeda insurgency after the U.S. invasion of Iraq in 2003.

In recent days Iraqi soldiers and police have been able to secure the center of Ramadi and push the militants back from some areas of the city.

Meanwhile, Iraq's most revered Shiite cleric, Grand Ayatollah Ali al-Sistani, on Friday urged the country's politicians to end all disputes in order to confront the political, economic and security challenges facing the country.

"It is important that the brothers (the politicians) should come out with final and drastic solutions for the problems," said al-Sistani's representative during a Friday sermon in the holy Shiite city of Karbala.

Al-Sistani's comments came as the Iraqi security forces, backed by Shiite militias, are struggling to regain control of territory lost to ISIS during a lightening offensive last year. Many Iraqis blame the rivalries among the country's political leadership for the humiliating defeat suffered by government forces.

In Friday's violence, police officials said a bomb exploded near an outdoor market in the Sunni town of Tarmiyiah, north of Baghdad, killing four people and wounding eight.

A bomb near a courthouse killed three people and wounded nine in the town of Mahmoudiyah, south of Baghdad.

Medical officials confirmed the death toll. All officials spoke on condition of anonymity because they are not authorized to speak to the media.

No group immediately claimed responsibility for the attacks.