Kamal Prasad Adhikari with the National People's Front of Nepal, who was a candidate in the Constitutional Assembly election set for April 10, was killed in his home Wednesday in Nepalgunj in the southern part of the Himalayan kingdom. Police say a local group fighting for the rights of ethnic Madhesi people in southern Nepal claimed responsibility for the shooting.

"I am extremely troubled by this tragic event and pass my sincere condolences to the victim's family," Jan Mulder, EU's chief election observer, said Thursday in a statement, Nepalnews.com reported. "The EU observation mission deplores violence. It has no place at all in a democratic election."

The U.N. Mission in Nepal said in a statement, "Violence and threats against candidates represent a serious obstacle to the creation of a free and fair atmosphere for the election and all efforts must be made to bring those responsible to justice."

CNN reported Adhikari was shot four times after he refused to leave the house.

The constituent assembly made up of 601 members will prepare a new constitution for the country and decide the fate of the kingdom's 239-year-old monarchy, now headed by King Gyanendra.