The government in the Democratic Republic of Congo has condemned challenger Etienne Tshisekedi's self-declaration that he is president, after incumbent Joseph Kabila was named the winner of last week's election.

Information Minister Lambert Mende says Tshisekedi is acting irresponsibly and violating the constitution by trying to subvert the decision of electoral authorities.

Congo's electoral commission declared Friday that Mr. Kabila defeated Mr. Tshisekedi 49 percent to 32 percent, with other candidates trailing far behind. The announcement sparked angry protests in the country in which four people were killed.

On Saturday, the situation remained tense in several cities in Congo, with sporadic gunfire erupting in the capital, Kinshasa.

Congolese immigrants in other countries staged protests against President Kabila. In London, police arrested 143 people Saturday evening after a group of angry protesters veered from the agreed location and started obstructing traffic and causing damage to shops and property. Protests were also held in Belgium, the former colonial power of the mineral-rich African country, and in Washington.

The United Nations, United States, European Union and African Union have appealed for calm.

Mr. Tshisekedi told VOA he considers the results to be a “provocation.” He said he sees himself as the country's elected president.

Congo's ruling party said President Kabila won the election fairly and that anyone alleging fraud must use the legal system to address their concerns.

Last week's presidential and legislative polls were the second free elections in Congo since it was torn apart by several years of warfare that ended in 2003.

Election observers from the African Union and U.S.-based Carter Center reported widespread irregularities, but urged Congolese parties and politicians to pursue any challenge to the results through the courts. Electoral officials released the results three days later than originally planned, citing logistical problems.

Human Rights Watch said 18 people were killed in violence leading up to the polls.