Shelling and heavy gunfire at the scene, about 19 miles north of the regional capital of Goma, have caused people to flee, the BBC reported Thursday.
The clashes are the worst since July.
The government has sent in additional troops as well as helicopter gunships.
Rwanda and Uganda have denied U.N. allegations that they are backing the rebels, also known as the Congolese Revolutionary Army.
M23 is comprised of soldiers who mutinied from the DR Congo army in April.
An estimated 500,000 people have been displaced since fighting began.