Shimla, Jul 27 (IANS): Inclement weather on Friday forced Union Transport and Highways Minister Nitin Gadkari to cancel his day-long visit to Himachal Pradesh.

Gadkari was scheduled to inspect the construction of Rohtang tunnel, one of the world's most challenging motorable projects at 3,000 metres above sea level, which will provide an all-season connectivity to the landlocked Lahaul Valley from Manali.

Gadkari was also coming to review other central government projects, particularly the national highways, during the visit, the Chief Minister's Office told IANS.

The most ambitious and expensive undertaking of its kind, the excavation of the 8.8-km long horseshoe shaped tunnel under the 3,978 metres Rohtang Pass in the Himalayas was completed in October 2017. Now civil engineering work is on, an official said.

"As per the current pace of work, most likely we will complete all civil engineering work by December 2019," an engineer involved in the tunnel construction told IANS.

"In all probabilities, the tunnel will be made operational by May-June 2020," he added.

The project is being built by the Border Roads Organisation (BRO), a wing of the Defence Ministry, in collaboration with Afcons, a joint venture with Strabag AG.

The tunnel's foundation stone was laid by United Progressive Alliance (UPA) chairperson Sonia Gandhi on June 28, 2010 in the picturesque Solang Valley.