The Jordanian authorities say an investigation into the bombings of three hotels in Amman has concluded that al-Qaeda in Iraq was responsible.
The attacks have stunned Jordan
Deputy Prime Minister Marwan Muasher said three non-Jordanian men had carried out the suicide attacks.
This contradicts an internet statement attributed to al-Qaeda that named four bombers - all Iraqis - including a husband and wife.
Wednesday night's blasts struck three hotels, killing 57 people.
Most of the victims were Jordanians attending wedding parties. Three Americans were also killed, a US embassy spokesman said.
Police have arrested scores of people.
The internet statement claiming to be from al-Qaeda in Iraq, the group led by Jordanian-born Abu Musab al-Zarqawi, claimed that four Iraqis wearing suicide belts had carried out the bombings, including a woman.
But Mr Muasher told a news conference that three people took part in the attacks "and there are no indications that a woman was among them".
"The investigation has shown that al-Qaeda was responsible for this attack, specifically the men of Abu Musab al-Zarqawi," Mr Muasher said.
"All those who took part in these operations are non-Jordanians. I will not go into details now. But there are no Jordanians among them."
Jordan, a close US ally and one of two Arab nations to have peace treaties with Israel, had been spared the al-Qaeda attacks that have hit other countries in the Middle East, winning it a reputation for safety.
Zarqawi, who has a $25m US bounty on his head, was jailed in Jordan for 15 years in 1996 but freed three years later under an amnesty.
He has subsequently been sentenced to death in Jordan for the 2002 murder of a US diplomat.
In August, his group claimed responsibility for a failed rocket attack on US Navy ships in the Jordanian port of Aqaba.
1. Vehicle explodes outside hotel after being stopped at a police checkpoint
2. In the most deadly attack, a bomb destroys a banquet room where a wedding reception was being held. Dozens injured by shrapnel
3. Suicide attacker detonates bomb in hotel bar, just before 2100 local time. Two senior Palestinian officials are among the dead