A vehicle environment detection system (40) in an ego vehicle (1), including a sensor arrangement (4) and a main control unit (8) is arranged to detect and track at least one oncoming vehicle (9), and to determine whether the ego vehicle (1) has entered a curve (17). The main control unit (8) is arranged to determine a common curve (12) with a radius (R), along which common curve (12) the ego vehicle (1) is assumed to travel, determine a measured oncome direction (13, 13′) of the oncoming vehicle (9) on the common curve (16), corresponding to an outcome angle (θtrack), determine a difference angle (δ) between the measured oncome direction (13, 13′) and an oncome direction (13) corresponding to if the oncoming vehicle (9) would be moving along the common curve (12), compare the difference angle (δ) with a threshold angle (θmax), and to determine that the oncoming vehicle (9) is crossing if the difference angle (δ) exceeds the threshold angle (θmax).