Frobenius manifolds and a new class of Extended affine Weyl groups of A-type.
	
	We present a new class of extended affine Weyl groups W^{(k,k+1)}(A_l) for 1 \leq k <l and obtain an analogue of Chevalley-type theorem for their invariants. We further show the existence of Frobenius manifold structures on the orbit spaces of W^{(k,k+1)}(A_l) and also construct Landau-Ginzburg superpotentials for these Frobenius manifold structures.