Congolese soldiers have been accused of barring UN troops and aid staff from an area where an operation with Rwandan troops is ongoing on a Hutu militia. A UN spokesman in the Democratic Republic of Congo told the BBC it was "deplorable", when so many displaced people were in desperate need of help. At least 3,000 Rwandan troops have crossed the border for the joint push on Rwandan FDLR fighters since Tuesday. The rebel group's leaders have been linked to the 1994 Rwandan genocide. DR Congo and Rwanda agreed last month to take joint action against the Hutu rebels of the Democratic Forces for the Liberation of Rwanda (FDLR), which is estimated to be more than 6,000-strong. The BBC's Thomas Fessy in the Congolese capital, Kinshasa, says hundreds more Rwandan troops entered North Kivu province on Wednesday, according to UN sources, following the 2,000 who crossed over the day before. Our correspondent says there has been no fighting reported so far as both armies appear to be still making preparations. Some troops are heading towards Rutshuru, 70km (45 miles) north of Goma, and others have been deployed near the strategic town of Sake, 30km (12 miles) west of the provincial capital. The UN Mission in the Democratic Republic of Congo (Monuc) said its peacekeepers and aid workers had been blocked by Congolese troops at checkpoints north of Goma. Monuc military spokesman Lt Col Jean Paul Dietrich told the BBC's Focus on Africa programme they had protested to the Congolese authorities. "We've just tried to negotiate since yesterday that our force should have the guarantee," he said. "Not only for us, the Monuc force, but as well all humanitarian [agencies] desperately need to get to those IDPs [internally displaced persons] in those areas. "And so far it seems that the blockade cannot be lifted and we deplore that and we cannot accept that. We will continue to keep up pressure." AFP news agency reported that a convoy of Indian UN peacekeepers and a Red Cross vehicle had been turned away. The Congolese authorities have said the operation to flush out the FLDR would last between 10 and 15 days, but Lt Col Dietrich said this would be a "very challenging task" in such a short timeframe.