A senior Uzbek official has linked this week's outbreak of violence, which killed at least 42 people, to al-Qaeda.
The violence has left Tashkent residents shocked and confused
It is the first time the government has made a direct connection to the group led by Osama Bin Laden.
However, the BBC's Monica Whitlock in Tashkent says this does not reflect the popular view in the city.
In the latest incident, a woman in the central Bukhara region was taken to hospital with serious injuries after apparently trying to blow herself up.
Reports say one person was killed as a result of the blast.
Ilya Pyagay, the deputy anti-terrorism chief at Uzbekistan's Interior Ministry, told the Associated Press that the insurgents "are Wahhabis who belong to one of the branches of the international al-Qaeda terror group".
The Wahhabis are members of a strict Islamic group originating in Saudi Arabia.
However, the term is traditionally used pejoratively to describe militant Islam in parts of the former Soviet Union.
"These are bandits who planned these attacks long in advance," Mr Pyagay added.
Svetlana Artikova, spokeswoman for the prosecutor-general, said the string of bombings and shootings that began on Sunday were "all part of one chain".
Our correspondent in the capital, Tashkent, says people are shocked and dazed by the unprecedented violence, the worst in five years, but the city remains calm.
Mr Pyagay said officials were trying now investigating whether the 20 alleged terrorists that died in a lengthy gun battle with police on Tuesday were Uzbek citizens or not.
Police said a suspected militant blew himself up on Wednesday night after a five-hour siege at a house in Tashkent.
Police claim the man had taken refuge in the house after setting off an explosion in the south-west of the city, which injured two policemen. There is no independent confirmation of how he died.
According to our correspondent, police say the dead man was a caretaker at the Islamabad mosque in old Tashkent.
Local people say his name was Mohammed Amin, an ordinary man not known as a member of any party or underground grouping.
The mosque is a large one where all local men come to pray, also not famous or known as a centre of radicalism.
President Islam Karimov said the insurgents were trying to break up Uzbekistan's alliance with the US.
US Secretary of State Colin Powell offered to help investigate the attacks in a telephone call to his Uzbek counterpart.
The US and Uzbekistan have been close allies since the 11 September 2001 attacks, after which the Uzbek government made its airspace and military facilities available to US forces operating in Afghanistan.