UNITED NATIONS, Jan. 21 (Xinhua) -- UN Secretary-General Antonio Guterres and the head of the UN Assistance Mission in Afghanistan (UNAMA) Tadamichi Yamamoto have strongly condemned a terrorist attack on a hotel in Afghan capital, Kabul.

In a statement released on Sunday, Guterres offered his deepest condolences to the families of the victims and wished a speedy recovery to those injured.

"He expresses his solidarity with the government and people of Afghanistan," said the statement delivered by his spokesperson.

At least 18 people were killed, including 14 foreign nationals, in the deadly attack on the Intercontinental hotel in Kabul. All the five attackers were also killed during gunfight with Afghan security forces. A 12-hour siege ended on Sunday.

According to UNAMA, Taliban has claimed responsibility for the attack and said five attackers entered the hotel to target Afghan officials and foreigners.

In a separate statement, Yamamoto, the UN secretary-general's special representative for Afghanistan, said that it is a "moral outrage that Taliban entered the hotel with the intention of killing civilians."

"There is simply no justification for this egregious attack, which is specifically prohibited by International Humanitarian Law and may amount to a war crime," he said.