A suicide attack outside a court in Pakistan's capital Islamabad killed 12 people and injured more than two dozen others on Tuesday, the country's interior minister said.

Mohsin Naqvi said a bomber was planning to attack the district courthouse but was unable to get inside, the BCC reported. 

Naqvi said authorities would prioritize identifying the bomber, and that those involved would be brought to justice. It remains unclear who carried out the attack.

Suicide blasts in Islamabad have been rare in recent years. Footage from the scene on Tuesday showed the remains of a burnt-out car and a police cordon in place.

Footage of the aftermath showed plumes of smoke rising from a charred vehicle behind a security barrier. 

Pakistani President Asif Ali Zardari said he "strongly condemned the suicide blast".

Pakistani Prime Minister Shehbaz Sharif has claimed that extremist groups "actively backed by India" were involved.

In a statement, he said that "terrorist attacks on unarmed citizens of Pakistan by India's terrorist proxies are condemnable".

In a separate incident on Monday, a car exploded in India's capital Delhi, killing eight people and injuring a number of others.

Indian Prime Minister Narendra Modi said following the attack: "The conspirators behind this heinous act will not be spared. All those responsible will be brought to justice, no matter how deep the conspiracy runs."