16 police personnel were among those who died in militant attacks in a Sunni-dominated area of Baghdad.
There are unconfirmed rumors from multiple sources in the Middle East that the al-Qaeda frontman was killed in a raid by US forces in Mosul, it said. However, the report cannot be verified until the intelligence firm gets other evidence.
'There has been communication between bin Laden and Zarqawi within the past two months, during which bin Laden suggested to Zarqawi to involve himself in attacks in the United States,' a US counter-terrorism official said.
The al-Tawhid wal-Jihad group said in a statement posted on the internet that it had killed the second American, believed to be Jack Hensley.
The late leader was reportedly issued a domicile certificate.
Jordanian security services foiled the plot in April last year. Jordanian officials say that had it been carried out, thousands of people would have died.
Last week, US forces launched an offensive near al-Qaim in Iraq and claimed to have killed scores of insurgents.
The Al Qaeda has called for a boycott of next month's elections in Iraq and endorsed Abu Musab al-Zarqawi as his deputy in the country, according to an audiotape broadcast by Aljazeera.
His visit to Iraq comes less than a week after a US air strike killed Abu Musab al-Zarqawi, the leader of the al Qaeda in Iraq.
The Sunday Times, London, quoted eye-witnesses as saying that US troops beat him to death.
The 17-page letter reveals that the outfit is facing problems in recruiting Iraqis putting in doubt the administration's claim that Iraq is a recruiting ground for terrorists.
Death came calling for the 71- year-old terrorist from the sky on Sunday morning in Kabul.
The United States has offered rewards amounting to USD 20 million (around Rs 127 crore) for tips on whereabouts of four top leaders of the Islamic State, a day after the terror group claimed responsibility for its first attack on American soil.