India will send three explorers to a depth of 500 metres under the sea in an indigenously built vessel, Samudrayaan, this year, an official said.

Engineers at the National Institute of Ocean Technology in Chennai have already designed the steel sphere that will house the aquanauts for their journey, he said.

However, the plan to send the Samudrayaan to 6,000 metres deep into the sea could be delayed due to difficulty in procuring the titanium sphere capable of withstanding pressure at those depths, the official, requesting anonymity, told PTI on the sidelines of the Indian Science Congress underway here.

He said a steel sphere can withstand pressure up to a depth of 500 metres, but will crumple as it cruises deeper, making titanium as the metal of choice.

"These are exclusive technologies and no country is ready to part with it. The Ukraine conflict has further aggravated the situation," the official said without elaborating.

India's has also set its eyes on achieving a human spaceflight by the end of next year.

The Ukraine conflict has already pushed the timelines for the human spaceflight to the end of 2024 and Indian Space Research Organisation (ISRO) plans to carry out an uncrewed mission to test and validate technologies for the Gaganyaan mission this year.

"It is not like sending a satellite to orbit. We cannot take chances when it comes to human beings. We are being cautious and careful. Globally, it took about 10 years for countries to develop human space flight capability, which we are doing in four," ISRO chairman S Somanath said.