At least 21 people have been killed and several wounded in latest attacks targeting Shias across Iraq.

Al Jazeera's Jane Arraf, reporting from Baghdad, said an improvised bomb exploded inside a Shia mosque in Dujail, 60km north of Baghdad, killing ten people and wounding at least 25 on Thursday night.

In a separate attack, two car bombs exploded in a market in the town of Ythrib in Salahadin province on Friday, killing ten people and wounding 18.

Another bomb near a Shia mosque in the largely Shia Turkmen town of Tuz Kharmatu, south of Kirkuk, killed one person and wounded six.

Sunni cleric Salah al-Nuaimi urged calm among Iraqis during a joint Sunni-Shia Friday sermon in Baghdad aimed at easing sectarian tensions.

"Enough is enough," al-Nuaimi told worshippers at a Baghdad mosque.

"We all love Iraq, we are all Iraqis and we want to be united, we want to stop the bloodletting, develop and build Iraq."

Attacks on Shia worshippers has increased during Ramadan. There has been no claim of responsibility for the latest attacks but many of the attacks are attributed to groups linked to al-Qaeda, which has traditionally escalated attacks during the holy month.

Group's Iraq branch, which has been gaining strength in recent months, frequently targets Shias, security forces and civil servants in an effort to undermine the Shia-led government in Baghdad.

According to the UN mission to Iraq, violence in June alone claimed the lives of 761 Iraqis and wounded 1,771 others.