The Thai military fired into the border province of Banteay Meanchey after midnight, "resulting in the deaths of two civilians who were travelling on National Road 56 by shelling", the Cambodian defence ministry said in a Facebook post.

Information minister Neth Pheaktra told AFP that at least four Cambodian civilians were killed by Thai shelling on Monday in the provinces of Preah Vihear and Oddar Meanchey which also border Thailand.

Around 10 other civilians were wounded, he said on Monday.

The Thai army has said one soldier was killed and 18 others were wounded since the fresh fighting began Sunday.

Both sides have blamed the other for instigating the renewed fighting, which saw Thailand launch air strikes and use tanks against its neighbour on Monday.

The conflict centres on a century-old disagreement over borders mapped during France's colonial rule in the region, with both countries claiming a smattering of boundary temples.