ISLAMABAD: Pakistan has expressed serious concerns over the unprovoked firing by the Afghan forces near the Chaman border. At his weekly news briefing here on Friday, Foreign Office Spokesperson Nafees Zakaria pointed out that border between the two countries is clearly demarcated and Pakistani teams were conducting the census drive in its own area which is our sovereign right. The spokesperson asked Afghanistan to stop firing against Pakistani forces. He said in case it does not stop, Pakistan reserves the right to respond to preserve its sovereignty and protect its civilians.