KABUL, June 5 (Xinhua) -- The United Nations Assistance Mission in Afghanistan (UNAMA) Tuesday denounced the suicide attack on a gathering of Afghan clerics seeking to promote peace in the country.

"The attack against a group of religious leaders who peacefully gathered in Kabul to issue a joint declaration that would contribute to a safer and more secure Afghanistan is totally unacceptable," Tadamichi Yamamoto, special UN envoy and head of the UNAMA, was quoted in an UNAMA statement.

He said he would continue to be outraged at those extremist groups seeking to derail efforts made in the interest of peace.

"No cause can justify such violence. Targeting civilians in this way is a clear violation of international law," he noted.

"The United Nations stands with the people and government of Afghanistan as they endeavor to build a peaceful future for their country," the statement said.

On Monday, at least 14 people, including seven religious scholars, have reportedly been killed and 17 others wounded when a suicide bomber detonated his explosive-packed vest at the gate of an Afghan university, where more than 2,000 clerics have gathered to highlight their stance against war and to call on the Taliban to accept the government peace offer.

The Taliban has reportedly denied their involvement in the incident.