Ilya Pyagay, Interior Ministry deputy anti-terrorism chief, said operations were continuing to capture suspected terrorists. At least 43 people — mostly alleged terrorists — have died this week in a series of suicide bombings and police shootouts.
"These are Wahhabis who belong to one of the branches of the international al Qaeda terror group," Pyagay told The Associated Press, referring to the strict strain of Islam in which bin Laden was raised. "These are bandits who planned these attacks long in advance."
Prosecutor-General spokeswoman Svetlana Artikova said Thursday the events were "all part of one chain."
The violence began with a bombing and attacks on police Sunday night, attempted suicide bombings and more attacks on cops Monday, more explosions and a stand-off between police and militants Tuesday and another standoff starting Wednesday.
It was the first unrest to hit this Central Asian nation since it became the United States' key ally in the region after the Sept. 11 attacks, hosting hundreds of U.S. troops at a military base near the Afghan border.
Pyagay said officials were trying to determine if the 20 alleged terrorists they said died in a stand-off Tuesday were Uzbek citizens or not. He said many had been carrying false passports.
Officers at the scene and witnesses said the clash was sparked after two suicide bombings that killed three police — contradicting official accounts that all 20 blew themselves up.
President Islam Karimov had initially hinted the attacks were connected to the extremist Islamic group Hizb ut-Tahrir, which has been firmly suppressed in the country. But the group denied involvement and it has no known links to terrorist violence.
The events also appeared to spark the start of a deeper crackdown on independent Muslims.
Human Rights Watch confirmed six arrests in Tashkent and the surrounding region, and another two women and three children detained overnight and later released, said Allison Gill, the group's Uzbekistan researcher. She said none of them appeared to have a connection to the violence.
"The volume of arrests just in the last 24 hours is high," she said. "It seems (authorities) are using this as a pretext to get people that they wanted anyway."
All land border crossings have been closed until further notice, the Border Protection Committee said. Tashkent's international airport continued to operate. Theaters canceled all performances until Monday, said a ticket agent at Tashkent's main Navoi Theater.
The latest violence was a standoff that ended early Thursday when officials said a militant blew himself up. Pyagay said it involved a "lone bandit" and no hostages, although police earlier had said several militants had taken hostages.
Oleg Bichenov, Tashkent city police anti-terrorism deputy chief, said a man who had barricaded himself in a house detonated explosives, killing himself.
A police major at the scene, who would not give his name, said the incident began when a booby-trap grenade detonated as police tried to enter the gate of the property about a half a mile from the Chorsu bazaar, where suicide bombers struck Monday, and that about 20 militants were holding "many" captives.
Bichenov declined to explain the discrepancies in accounts of the standoff, which began late Wednesday. Uzbekistan is an authoritarian country where information is strictly controlled, contributing to the confusion.
Dozens of troops and officers and a unit of eight police dogs surrounded the house. Authorities cordoned off a large area around the building and used buses to evacuate neighbors, while soldiers pointed Kalashnikovs at onlookers and shouted at them to move back.
The Interfax news agency said there was an unknown number of casualties in the grenade blast. Russia's Channel One television said three people were wounded, and ITAR-Tass said one police officer was lightly injured.
An AP photographer saw a body being transported from the scene Thursday afternoon as soldiers still guarded the area, checking identification documents and only allowing residents to enter the neighborhood.
Police reportedly arrested at least 30 fugitive militants on Wednesday, but Bichenov declined to confirm how many had been arrested.
"The number will be changing, and I hope it will be going up," he told AP earlier. "We are continuing to search for suspects and making arrests."
Bichenov said those in custody were being questioned at length — but that interrogations so far found that none were members of Hizb ut-Tahrir.
Uzbekistan's tiny opposition, banned by Karimov's authoritarian regime from working openly, fears that this week's attacks will deepen a widespread crackdown against dissent and independent Islamic mosques. Thousands have been jailed, drawing international condemnation.
Uzbekistan is a little larger than California and home to 25.9 million people, according to the CIA World Factbook. It is 88 percent Muslim.