HOLY CITY OF KARBALA, Iraq: As security has been beefed up in the holy cities of Najaf and Karbala marking Ashura – Moharram 10 when Abi Al-Ahraar Al-Imam al-Hussein was martyred – that falls this year on Sunday December 27, millions of Husseini mourners are heading to Karbala to commemorate the heartrending occasion.

Karbala police spokesman Major Alaa Abbas said 25,000 additional security forces had been sent to Karbala, along with specialized vehicles and police dogs to detect explosives.

Helicopters are also keeping watch from the skies.

Thursday's attacks underscored extremists' efforts to exploit security gaps, targeting relatively unprotected pilgrims travelling to Karbala even as authorities fortified the area in and around this holy city.

“The terrorists are using the most ugly ways to kill innocents and hit national unity,” Maj. Abbas said.

As many as 25 Husseini mourners were martyred in Hilla in the central province of Babil when they struck a roadside bomb.

Also on Thursday, Iraqi forces dismantled nine explosive devices north of the holy city of Karbala as violence grips the country ahead of Ashura.

Security officials told the Voices of Iraq news agency that Iraqi police defused nine bombs just north of Karbala.

"Anti-bomb experts managed to defuse the bombs without casualties," said Iraqi Maj. Alaa Abbas.

An improvised explosive device, meanwhile, exploded in a restaurant just north of Karbala, leaving as many as nine people martyred.