KIGALI, Rwanda (CNN) -- Rebels admitted for the first time on Wednesday that their territory in the eastern part of the Democratic Republic of Congo had come under air attack. Meanwhile, President Laurent Kabila told the country's former colonial ruler, Belgium, that he would introduce pro-democracy reforms within two months.

The rebels confirmed that Zimbabwean planes had bombed the eastern shore of Lake Tanganyika -- an admission that came one day after Congolese state radio said the government and its allies had hit an aircraft in Kalemie, a port 500 kilometers (310 miles) south of the rebel stronghold at Goma.

"There was bombing of Kalemie. But I don't know what the target was," rebel leader Ernest Wamba dia Wamba said from the northern city of Kisangani. "As far as I know, nothing happened and there were no casualties."

"If they are using more precise aircraft, there is a ground for us to be extra worried," Wamba said. "We are waiting for them. We are not going let them overrun us."

In the past, rebel military commanders have dismissed the Zimbabwean air force, saying its planes were dropping bombs from too high an attitude to hit targets accurately. They said the Zimbabweans were not flying low for fear of being hit by surface-to-air missiles.

The rebels are backed in arms and weapons by neighboring Rwanda and Uganda, who accuse Kabila of failing to rid the common border of insurgents fighting their governments.

So far, the government -- backed by troops, tanks and planes from Zimbabwe, Angola, Namibia and Chad -- have had little success in halting the rebels.

Last week, Zimbabwe sent 1,500 military police to eastern Congo, apparently to restore discipline and reduce desertion among its 8,000 troops.

Kabila arrives in Brussels

Kabila, who is in Belgium for what he has called a two-day "working visit," said after his arrival late Tuesday that he would allow political parties soon.

"The people should decide who should lead them. We have said that it is better to liberalize activities (of political parties) and that will take place, according to law, in two months."

"Every Congolese is free to create an association, a political party," he added.

Kabila announced a two-year transition to democracy shortly after he took power in early 1997, after toppling President Mobutu Sese Seko of what was then called Zaire.

Kabila's government has come under criticism both at home and abroad for an apparent lack of resolve to bring democracy to the country and alleged human rights abuses.

The United Nations on Tuesday called on all states to strengthen controls on illicit arms shipments to the country, following a devastating report on how Rwandan Hutu fighters had joined the strife in Congo.

The Associated Press and Reuters contributed to this report.