KATHMANDU, Nepal — Nepal's upper house of parliament on Thursday signed off on a proposed constitutional amendment that would change the nation's political map to include strategically important territory also claimed by India.

Already approved by the lower house, the proposed amendment still needs to be signed by the president before becoming official.

The proposed map has been strongly criticized by India and soured relations between the South Asian neighbors and a formal constitutional amendment is likely to further strain ties.

Prime Minister Khadga Prasad Oli's government has pushed for the amendment and it has widespread public support.

Nepal has long claimed the areas of Limpiyadhura, Kalapani and Lipu Lekh in accordance with an 1816 Sugauli treaty with the British Raj, although the areas have remained under the control of Indian troops since India fought a war with China in 1962.

India does not recognize Nepal's claims, and says talks should be held on any outstanding boundary issues.

The border dispute between the two countries heated up again last month when India opened a Himalayan link road through one of the disputed regions that lies at a strategic junction with Tibet and China.

The 80-kilometer (50-mile) road, inaugurated by Indian Defense Minister Rajnath Singh, cuts through the Lipu Lekh Himalayan pass, considered one of the shortest and most feasible trade routes between India and China.

Nepal fiercely contested the inauguration of the road, seeing it as an incursion and a stark example of bullying by its much larger neighbor.