An official in the Democratic Republic of Congo's North Kivu province has accused neighbouring Rwanda of supporting and arming a rebel group in a volatile border area.
Erneste Kyaviro, spokesman for North Kivu governor Julien Paluku, told the Reuters news agency on Tuesday that Rwanda had invaded eastern DRC.
"It's not a rebellion, it's an invasion," he said, referring to the ongoing fighting between M23 rebels and Congolese troops.
"We didn't think that the Rwandan army would be throwing all its might into Congolese territory."
Kyaviro appealed for a forceful response by the international community, especially Western nations, to pressure Rwanda to halt its alleged support for the rebellion.
"You don't need a single shot fired to stop Rwanda," he said, saying countries like the United States, Britain, Norway and Belgium should halt their aid to landlocked Kigali to put an end to M23 operations in Congolese territory.
"We need the help of the whole world," he said, adding Rwanda had deployed elite troops along the border near Goma.
Last month, a United Nations group of experts published a report with an addendum that described Rwandan military officials providing M23 rebels with weapons, ammunition and recruits.
The rebels, who have seized several towns and villages in Rutshuru territory in eastern DRC, call themselves M23 after a March 23, 2009, agreement with the government that saw them integrated in the national army.
They had previously been fighting under the National Congress for the Defence of the People (CNDP), which was led by Laurent Nkunda, a rebel commander who was once backed by Rwanda and is believed living in the same country.
The fighting started in March when the soldiers mutinied, demanding better pay and living conditions.
But officials say the mutiny was triggered by an arrest warrant by the International Criminal Court for M23 leader Bosco Ntaganda, who is wanted for war crimes.
Ntaganda had been made a general in the DRC army after the March 2009 agreement.
Rwanda denies accusations of backing the rebels, although UN officials say M23 rebels are apparently well-equipped and growing in number.
The rebels have driven back the Congolese government army in a determined offensive over the last few days, forcing UN peacekeepers in the country to withdraw into isolated operating bases in the hilly countryside.
One Indian UN soldier was killed in a rebel attack last week.
The rapid M23 rebel advance has opened the way for a possible assault on the North Kivu provincial capital Goma, where UN peacekeepers have reinforced their positions.
Residents reported that UN armoured vehicles were guarding major crossroads of the city and also patrolling the outskirts.
The fighting in North Kivu province has displaced thousands of civilians and raised tension between uneasy neighbours in the Great Lakes region at the heart of Africa.