Militants have been carrying out what they say are co-ordinated attacks on the Afghan capital Kabul and other targets in Afghanistan.
Foreign embassies, Nato's HQ and the Afghan parliament have all come under attack in Kabul, where multiple blasts and gunfire were heard.
The Taliban said "tens of suicide attackers" had struck in Kabul and Logar, Paktia and Nangarhar provinces.
It is the first major attack on Kabul in more than six months.
Nato said it had reports of attacks in seven locations in Kabul.
The British embassy was one of the targets, with two rockets hitting a guard tower. A rocket-propelled grenade was also fired into a house used by British diplomats, witnesses told Reuters news agency.
A medical source in Kabul told the Associated Press news agency five people had been wounded in the attacks, and at least two militants are reported dead in the city.
According to another unverified report, from Afghan broadcaster channel Shamshad TV, eight people were also wounded, and two militants killed, in an attack in the eastern city of Gardez, in Paktia.
At least seven large explosions were heard in central Kabul and gunfire erupted from various directions in the
heavily barricaded diplomatic zone.
Residents were reportedly running for cover and sirens wailing in the Wazir Akbar Khan district.
Some explosions were also heard near the parliament building in western Kabul and police said it was under attack.
A number of MPs joined the fight against the insurgents, shooting at them as they tried to storm parliament, Kandahar lawmaker Naeem Hameedzai Lalai told reporters.
"I'm the representative of my people and I have to defend them," he said.
Rockets were reportedly fired at the Russian embassy and smoke was said to be billowing from the direction of the German embassy.
The US embassy confirmed there were attacks nearby. It said: "The embassy is currently in lockdown... all compound personnel are accounted for and safe."
Britain's Foreign Office said it was "in close contact with embassy staff".
AFP news agency reported that the newly built Kabul Star hotel was on fire.
Kabul resident Idris Ghairat, who lives near the hotel, told the BBC: "I can see the smoke rising. The fighting is around us and I have heard the blasts and gunfire. The security forces have taken position on top of all government buildings close to the hotel."
Another attack appeared to target a Nato base known as Camp Warehouse on the outskirts of the city, where Turkish and Greek Nato forces were trying to repel militants.
The BBC's Bilal Sarwary in Kabul says there are also reports of a suicide attack that has closed the centre of the eastern city of Jalalabad.
Police said suicide bombers had attacked the airport there.
Abdulhadi, who works for the World Food Programme in Jalalabad, told the BBC: "The US air base was under attack. We heard loud explosions and had to take cover in a bunker."
Militants also took over a government building in Pul-e-Alam, capital of Logar province, police said, and a gun battle was under way.
In Gardez, capital of Paktia province, militants took over a building where university students were staying.
In the city of Kundoz, 15 suspected militants were arrested over an alleged plot to launch attacks, an official told BBC News.
Mirwais Yasini, an MP from the eastern province of Ningarhar, told BBC News: ''This shows the Taliban don't want peace.
"They don't want to negotiate. They are not serious. They want to continue the killing of innocent people. But these attacks also show a clear intelligence failure. Where was the intelligence to prevent co-ordinated attacks?''
There is normally a surge in the number of Taliban attacks at this time of year following a relative lull in winter, when militants find it more difficult to move around.