DINARD, France (Reuters) - Democratic Republic of Congo’s (DRC) new president must swiftly form a government and seize the moment as groups, anxious for political change, lay down their arms, the head of the UN mission in Congo warned on Saturday.

Felix Tshisekedi’s victory in the Dec. 30 elections, while marred by widespread accusations of fraud, led to the first transfer of power via the ballot box in DRC. Safeguarding Congo’s fragile security situation will be one of the key tasks for Tshisekedi, who has yet to deliver the final act of the transition.

“The Congolese people are in this expectation, we must not disappoint them,” the head of the UN stabilization mission in DRC (MONUSCO) Leila Zerrougui said in an interview on the sidelines of the G7 foreign ministers meeting in western France.

“This wait should not last too long because ... nature abhors a vacuum, and so bad things will happen if good things do not occur,” she said.

In some provinces of Congo, armed groups have decided to lay down their arms, she underlined, citing Kasai (center), Ituri (east), Tanganyika (east) and even some parts of the eastern province most stricken by violence, Kivu.

“It’s an extremely important dynamic that ought to be seized upon”, she said in Dinard where she was invited to talk about sexual violence as a weapon of war.

Amid a resurgence of hostility between African neighbors Uganda and Rwanda, the seasoned Algerian diplomat applauded Kinshasa’s position regarding foreign rebels seeking shelter in Congo.

“The Congolese government has shown very clearly that it does not agree with being a rear base used to destabilize neighbors,” she said, citing several deportations of Rwandan rebels.

As the trial over the killing of two U.N. sanctions monitors, Zaida Catalan and Michael Sharp in 2017, is close to entering its second year, she hoped for a positive signal from the new government. Tshisekedi has promised to give impetus to the fight against corruption and the efficiency of the judicial system.

“We do not want to interfere, as long as justice is following its course. The trial is ongoing, but to us it’s extremely important. This trial can inform us on the positive change at stake with the new government,” she added.