Ranchi, Aug 7 - The Ranchi-Patna national highway has been closed near Jharkhand's Ramgarh district because of damage caused by the underground mine fire, an official said Friday.

The decision to close the national highway was taken as cracks have appeared on the highway, used by thousands of heavy and light vehicles.

'We have closed the national highway. The alternative routes have been finalised. The project report of the diversions has been completed and work will start in a day or two. The diversions will be completed in two months,' Ramgarh Deputy Commissioner Arun Kumar Sinha told IANS.

The underground mine fire in the closed mines of Central Coalfield Limited (CCL) near Kuju in the district came close to the national highway nearly a month ago and the flames and smoke emanating from underground were clearly visible. The fire has posed threat to about a three km stretch of the highway.

Ramgarh district administration had announced that the diversion would be completed in a fortnight, but could not meet the deadline.