Heavy fighting is continuing in the Afghan city of Kunduz, one day after government forces launched a counter-attack to reclaim it from the Taliban.Two US air strikes on Tuesday halted an attempt by insurgents to seize the airport, the army`s stronghold.Afghanistan`s spy agency says the strikes killed the Taliban leader in the province and his deputy, but the Taliban has denied this.The capture of Kunduz represents the militants` biggest victory since 2001.On Tuesday the United States acknowledged the seizure of Kunduz as a setback, but says it remains confident that Afghan security forces can re-take the northern city.Overnight there were clashes around the city, but it remains unclear just how much of it remains under government or Taliban control.