Iraq's prime minister on Tuesday denied reports he will form an alliance with the nation's leading Shiite parties ahead of national polls in January.

Nouri al-Maliki said the suggestions that he will create an election bloc with the rival Shiites of the Supreme Iraqi Islamic Council and the followers of anti-American cleric Muqtada al-Sadr, are "not true."

But al-Maliki also welcomed all parties _ including his Shiite rivals _ to come under the umbrella of his party for the vote or afterward.

"We said if they want to form fronts now, they are welcome to, and if they want to form them after elections, they are also welcome to do so," al-Maliki told reporters. "The door is open for all."

Earlier this year, the Supreme Council and the Sadrists joined together to form the Iraqi National Alliance. Both parties enjoy close ties to Iran. The bloc also includes smaller Shiite, Sunni and secular groups.

It replaces a Shiite alliance that won the last election in December 2005, dominating the 275-seat legislature and securing al-Maliki, whose Dawa party was part of the alliance at the time, the prime minister's job.

The alliance has emerged as the main threat to al-Maliki's hopes to win another four-year term at the helm after elections.

Al-Maliki rejected joining the new Shiite bloc and instead has formed a broad coalition _ known as the State of Law list _ that emphasizes secular policies and reconciliation with Sunnis after years of sectarian bloodshed.

He has staked his political reputation upon his ability to boost security in a country weary of years of bloodshed. But his once dominant political position has taken a hit by two major bombings in Baghdad since August.

The most recent attack took place Oct. 25 in central Baghdad, killing 155 people and wounding some 500. The bombings seemed designed to paint al-Maliki as a leader incapable of providing security, undermining much of his political support.

On Tuesday, the prime minister blamed Baathists, supporters of former dictator Saddam Hussein, for the attacks, and said "their aim is to undermine the elections."

He said 73 people _ all with ties to the outlawed Baath party _ have been detained in connection with the attacks, which struck the Justice Ministry and the Baghdad provincial administration building, akin to city hall. The August attacks targeted the foreign and finance ministries, also in the heart of Baghdad.