A series of suicide attacks by the Taliban militants in Afghan capital Kabul on Tuesday left 12 people including five suicide bombers dead and injured 21 others, including four in the U.S. embassy.

The first blast occurred at 13:20 local time (0850 GMT), followed with gun battle.

In the first step, the militants occupied an under construction tall building close to the fortified U.S. embassy and begun attacking the embassy compound with light arms and rocket propelled grenades.

Four Afghans were injured in the attack on the embassy compound, none with life threatening injuries. They included three Afghan visa applicants and one local contract guard, according to a statement posted on the U.S. embassy website.

Meantime, Afghan Interior Ministry admitted in a statement released late evening that militants targeted four places in the capital city Kabul on Tuesday which "had left seven people including four police and three civilians dead."

"Seventeen others including nine policemen and eight civilians had sustained injuries," the Interior Ministry said.

Five suicide bombers have either been killed by security forces or died in their detonations, it added.

The situation has been brought under control, the statement emphasized. However, it said that search operation is underway inside the under-construction building in case any suicide bomber is hidden.

Meanwhile, Qari Yusuf Ahmadi who claims to speak for the Taliban outfit in talks with media via telephone from unknown location claimed responsibility for the attacks, adding a group of Taliban fighters equipped with arms and suicide vests targeted the U.S. embassy and NATO-led forces headquarters inflicting huge casualties.

Afghan President Hamid Karzai termed the multiple attacks as coward terrorist act and strongly condemned it.

"The enemy does everything they can to affect the process of transition of security responsibilities to the Afghan government. The attack cannot stop the process of transition but rather embolden our people's determination in taking over the security responsibility of their country," President Karzai said in a statement released by his office.

The process of taking over security charge by Afghan security forces from over 140,000-strong NATO-led troops with nearly 100, 000 of American, begun in last July, is scheduled to be completed by the end of 2014.