India Prime Minister Narendra Modi has inaugurated one of the most ambitious and strategic railway projects the nation has ever built.

Modi visited the Chenab bridge on Friday with tight security, waving an Indian tri-colour flag before boarding a test train that passed through picturesque mountains and tunnels to reach an inauguration ceremony for another high-elevation bridge named Anji.

India is committed to efforts to develop its restive territory of Jammu and Kashmir, Prime Minister Narendra Modi said on Friday, accusing neighbours Pakistan of seeking to destroy livelihoods there with April's deadly attack on tourists.