India's space programme suffered a huge setback on Saturday after it lost contact with an unmanned spacecraft moments before it was due to make a historic soft landing on the Moon.

Prime Minister Narendra Modi sought to comfort glum scientists and a stunned nation from the lunar programme's command centre in Banglalore, saying India was “proud” and clasping the visibly emotional mission chief in a lengthy bear hug.

Blasting off in July, India had hoped to become just the fourth country after the United States, Russia and regional rival China to make a successful Moon landing, and the first on the lunar South Pole.

But in the early hours of Saturday India time, as Modi looked on and millions watched with bated breath nationwide, Vikram, the lander named after the father of India's space programme, went silent just 2.1 kilometres above the lunar surface.

“The Vikram lander descent was (going) as planned and normal performance was observed,” Indian Space Research Organisation (ISRO) chairman Kailasavadivoo Sivan said.

“Subsequently the communication from the lander to the ground station was lost,” he said in a stunned operations room. “The data is being analysed.”

The Chandrayaan-2 ( “Moon Vehicle 2”) orbiter, which will circle and study the Moon remotely for a year, is however “healthy, intact, functioning normally and safely in the lunar orbit”, the ISRO said.

Consoler-in-chief

Freshly re-elected Modi had hoped to bask in the glory of a successful mission, but on Saturday he deftly turned consoler-in-chief in a speech at mission control broadcast live on television and to his 50 million Twitter followers.

“Sisters and brothers of India, resilience and tenacity are central to India's ethos. In our glorious history of thousands of years, we have faced moments that may have slowed us, but they have never crushed our spirit,” he said.

“We have bounced back again ... This is the reason our civilisation stands tall,” he said in Bangalore. “When it comes to our space programme, the best is yet to come.”

Chandrayaan-2 took off on July 22 carrying an orbiter, lander and rover almost entirely designed and made in India, a week after an initial launch was halted just before blast-off.

ISRO had acknowledged before the soft landing that it was a complex manoeuvre, which Sivan called “15 minutes of terror”.

It was carrying rover Pragyan — “wisdom” in Sanskrit — which was due to emerge several hours after touchdown.

The rover was expected to explore craters for clues on the origin and evolution of the Moon, and also for evidence on how much water the polar region contains.

According to Mathieu Weiss, a representative in India for France's space agency CNES, this is vital to determining whether humans could one day spend extended periods on the Moon.

It would mean the Moon could be used as a pitstop on the way to Mars, the next objective of governments and private spacefaring programmes such as Elon Musk's Space X.

Ambitious programme

Asia's third-largest economy also hopes to secure lucrative commercial satellite and orbiting deals in the competitive market.

China in January became the first to land a rover on the far side of the Moon. In April, Israel's attempt failed at the last minute when its craft suffered an engine failure and apparently crashed onto the lunar surface.

The Chandrayaan-2 space mission — India's most ambitious so far — stood out because of its low cost of about $140 million.

The US spent the equivalent of more than $100 billion on its Apollo missions.

India is preparing Gaganyaan, its first manned space mission, with the air force announcing on Friday that the first level of selection of potential astronauts was complete.

The South Asian nation also hopes to land a probe on Mars. In 2014, it became only the fourth nation to put a satellite into orbit around the Red Planet.