KINSHASA (Reuters) - The U.N. peacekeeping mission in the Democratic Republic of Congo will pause its withdrawal, with no timeline set for the next phase following the initial one in June, the government and mission said.

In September last year, President Felix Tshisekedi asked the mission to fast-track the withdrawal of peacekeepers who were deployed to the Central African country to quell insecurity caused by armed groups fighting over territory and resources.

The first phase of the withdrawal, in South Kivu province, was completed on June 25, Congo's ambassador to the United Nations, Zenon Mukongo Ngay, said on Monday. It had been scheduled for completion by April.

Ngay indicated that conditions had not yet been met for the next phase, however, blaming neighbouring Rwanda for an escalation of clashes in the restive east of Congo.

"In view of Rwanda's continued aggression in North Kivu, the next phase of withdrawal, phase 2, will be undertaken when conditions allow, following ongoing joint assessments," he said in a speech at the U.N. Security Council.

Congo and the United Nations have long accused Rwanda of backing the M23 rebel group, allegations Kigali has denied.

Bintou Keita, head of the U.N. mission, said there was "no timeline" for a withdrawal from North Kivu or Ituri provinces.

"Don't ask me what's next," Keita told reporters at the United Nations in New York on Monday. "What's next, as we said, (is) we pause, we prepare, and we see what comes next based on the reality on the ground."

Congo's foreign minister Therese Wamba Wagner said the government wanted to avoid creating a security vacuum.

"When it comes to North Kivu, we will take into account the developments that we see on the ground before making responsible decisions and starting this process when the most favourable conditions are met," she told reporters in Kinshasa.

(Reporting by Benoit Nyemba in Kinshasa, Sonia Rolley in Paris and Michelle Nichols in New York; writing by Portia Crowe; editing by Mark Heinrich)