NAIROBI, Kenya — When the United Nations hosts a donor conference next week to raise $1.7 billion for the violence-racked Democratic Republic of Congo, one important country will not attend: Congo itself.

The government of President Joseph Kabila has said that it will boycott the gathering, denying that his central African nation faces a humanitarian crisis at all.

The move, which took some diplomats by surprise, was another sign of the increasing isolation of the government of Mr. Kabila, who has faced internal rebellion and international criticism for holding on to power in defiance of constitutional term limits.

The government’s increasingly bellicose stance comes as it has been blasting what it calls international “meddling” in the country’s politics. Under intense international pressure, Mr. Kabila’s government will hold new elections in December, but it has rejected any outside assistance with the poll.