KABUL, Oct. 3 (Xinhua) -- The United Nations Assistance Mission in Afghanistan (UNAMA) on Wednesday expressed concern over increased election-related violence and attacks, the UNAMA said in a statement.

"The UNAMA expresses its concern around the level of violence early in the campaigning period for the 20 October parliamentary elections, including intimidation and attacks against candidates, their agents and supporters," the statement said.

The mission condemned a latest attack that killed at least 14 civilians and wounded a further 42 when a suicide attacker struck at a campaign rally in eastern Nangarhar on Tuesday.

"Since campaigning formally commenced on 28 September, there have been several attacks resulting in the killing of a candidate and three security guards of another candidate, as well as the shooting of a further candidate's agent and son," the statement added.

The UNAMA also urged all actors to halt all violence and intimidation against candidates and voters, the statement read.

"I am outraged by attacks deliberately targeting civilians seeking to exercise their basic right to participate in elections," Tadamichi Yamamoto, UN Secretary-General's special representative for Afghanistan, was quoted in the statement as saying.

"This violence, including Tuesday's reprehensible attack in Nangarhar, is an assault on the constitutional rights of the people of Afghanistan." he said.

The electoral campaign for the Oct. 20 Afghan parliamentary elections began Friday across the country.

Around 2,691 candidates from 33 out of 34 provinces (excluding Ghazni) will run for the parliament's 249 seats, another milestone in the war-torn country's electoral history.