Sri Lanka has asked China to defer the planned visit of a Chinese survey ship to the island country after an objection from India, a government source told Reuters on Sunday.

The Chinese research and survey vessel, Yuan Wang 5, was still on its way to Sri Lanka’s Hambantota port. It is scheduled to arrive there on August 11, according to shipping data from Refinitiv.

India worries that the Chinese-built and leased port of Hambantota will be used by China as a military base in India’s backyard. The $1.5 billion port is near the main shipping route from Asia to Europe.

China’s foreign ministry did not immediately respond to a request for comment on Sunday.

Last week, a spokesperson for the Sri Lankan government said the ship was only stopping at Hambantota for refuelling.

China is one of Sri Lanka’s biggest lenders and has also financed airports, roads and railways, unsettling India.

As Sri Lanka battles its worst economic crisis in seven decades, India this year alone has provided it nearly $4 billion in support.

Diplomatic relations between India and China have been strained since clashes in 2020 between troops along a remote Himalayan border. At least 20 Indian and four Chinese soldiers were killed in the fighting, which led to a massive build-up of troops on both sides.

Foreign security analysts describe the Yuan Wang 5 as one of China’s latest space-tracking ships, used to monitor satellite, rocket and intercontinental ballistic missile launches.