A powerful blast followed by sporadic gunfire hit Afghanistan's capital Kabul on Tuesday near the city's heavily fortified “Green Zone”, an area home to government buildings and foreign embassies, police officials said.

At least three people were killed and seven wounded, said Ghulam Dastagir Nazari, a health ministry spokesperson, adding that clashes were continuing.

A senior security official said the blast appeared to have been caused by a car bomb and the apparent target was the residence of a member of parliament.

Two gunmen were still in the area and clashing with Afghan security forces, the official said.

The city's Emergency Hospital said in a tweet it had so far received six people wounded in the attack.

A second loud blast followed by rapid gunfire rocked Kabul, less than two hours after the first explosion, AFP correspondents reported.

The second blast was also followed by some smaller explosions in a central part of the city, not far from the heavily fortified Green Zone.

No militant group immediately claimed responsibility.

Minutes after the blast hundreds of civilians in Kabul came out onto the streets and chanted Allahu Akbar (God is great) to express their support for Afghan government forces and opposition to the Taliban.

The overnight march spilled across the city with mostly men and some women joining in the demonstrations, carrying candles and Afghan flags to signal united opposition to the hardline group.

“The whole world can choose to be silent about what is going on in Afghanistan but we can't and won't stay quiet anymore ... we will stand side by side with our security forces until our last breath,” said a demonstrator in Kabul on condition of anonymity.

Last week residents in western Herat braved the streets despite nearby fighting to protest against the Taliban. Other cities quickly organised to join the chant from their homes in the evenings, as a message of support for embattled security forces.

Clashes between Afghan forces and the Taliban have intensified across the country with the insurgent group gaining control over checkpoints, trading posts and infrastructure projects.

Afghan forces appealed to residents of the southern city of Lashkargah to leave their homes and stay away from areas where the Taliban were taking control, as they intend to launch operations against the group.

The Taliban said their fighters in Kabul killed a district governor of central Maidan Wardak province on Tuesday, the latest in a series of killings by the insurgent group aimed at eliminating senior government officials and social activists.