Iraqi security forces are poised to launch a major crackdown in volatile Diyala province, the Interior Ministry said on Sunday, the latest in a series of operations aimed at stabilising the country.

Sunni Islamist al Qaeda has sought to stoke tensions in the religiously and ethnically mixed northeastern province, which has seen a string of suicide bombings in recent months.

The crackdown will be the latest Iraqi-led offensive aimed at stamping government authority on areas once in the hands of Sunni Arab insurgents or Shi'ite militias.

U.S. and Iraqi officials say a campaign against al Qaeda in the northern city of Mosul and surrounding Nineveh province has helped reduce violence there. Other operations have targeted Shi'ite militias in the southern provinces of Basra and Maysan.

"Soon, the security forces will be in Diyala to play the role they played in Basra and Maysan and Mosul, and Diyala could be the last stage," Iraqi Interior Ministry spokesman Major-General Abdul-Kareem Khalaf told a news conference.

He did not give a date for the start of the Diyala crackdown and it was unclear if he meant the offensive would be the last major operation aimed at securing the country.

Overall attacks across Iraq were down 85 percent in June from a year ago, the Iraqi military said last week.

U.S. forces have been conducting security operations in Diyala since the beginning of the year and will take part in the new Iraqi push, a spokesman said.

The success of Iraq's recent operations has given the government confidence, which has been most apparent in calls by Iraqi leaders for a timetable for the withdrawal of U.S. troops as part of a security deal being negotiated with Washington.

IRAQI FORCES NEAR "SELF RELIANCE"

Iraqi security forces were taking the lead in more than 75 percent of security operations, national security adviser Mowaffaq al-Rubaie told CNN television.

"We can see in a very short period of time, the Iraqi security forces will reach . self reliance . We can relax the requirements for foreign troops in this country," he said.

Iraqi and U.S. officials have been working on an agreement to provide a legal basis for American troops to remain when a U.N. mandate expires at the end of the year.

But negotiators had ended efforts to reach a formal Status of Forces Agreement before President George W. Bush leaves office in favour of an interim deal, the Washington Post said on Sunday, citing senior U.S. officials.

In the past week Iraqi leaders have spoken of only agreeing what they call a memorandum of understanding.

The Washington Post quoted one U.S. official close to the negotiations as saying "we are talking about dates", even though Bush has previously rebuffed calls for a timetable.

Iraq is a major issue in November's presidential election battle between Republican John McCain and Democrat Barack Obama. McCain supports the Bush administration's current strategy, while Obama has called for a timetable for withdrawal.

Iraqi Vice President Tareq al-Hashemi, a Sunni Arab, added his support for a withdrawal timetable.

"Iraqis must know when the American and other forces will leave Iraqi land. It is our right to know, and know the truth of where the situation stands, if there is an intention for American forces to leave or not," Hashemi told Iraqiya state television in an interview broadcast on the weekend.

The Post said the "bridge" security document would likely cover only 2009, and be limited in scope, allowing basic U.S. military operations to continue once the U.N. mandate ended.

Iraq has rejected a number of Washington's demands, insisting they infringe on the country's sovereignty.

There is strong domestic pressure in Iraq to set dates for a withdrawal of U.S. forces, especially with violence at a four-year low and with Iraqi security forces getting larger.

Prime Minister Nuri al-Maliki's political opponents would also likely try to exploit the issue of an undefined U.S. troop presence in provincial elections later this year.