West Bengal has the highestmortality rate in the country at 12.8 per cent, Inter Ministerial Central Team (IMCT) leader Apoorva Chandra wrote in his final observations to state Chief Secretary Rajiva Sinha, before leaving for Delhi on Monday."This extremely high mortality rate is a clear indication of low testing, weak surveillance and tracking," Chandra said in the letter.A discrepancy has been brought to the fore in the number of COVID-19 cases reported by the state in its medical bulletins and its communication with the Union government, Chandra noted in the letter.The team, led by Chandra, returned to the national capital after having completed two weeks of stay in the city.