At least 320 Indians remain missing and around 400 others are stranded on the Chinese side following devastating flash floods along the Nepal-Tibet border, the Ministry of External Affairs (MEA) said on Friday.
India is ready to extend all possible help to Kathmandu in its rescue efforts, the ministry said.
The MEA said 153 Indian nationals stranded on the Chinese side have safely crossed over to Nepal.
Twenty-one Indians arrived in New Delhi on Friday afternoon, a day after reaching Kathmandu from flood-affected areas of Nepal, MEA spokesperson Randhir Jaiswal said.
The Indian nationals, who are from Tamil Nadu, were received at the airport by External Affairs Minister S Jaishankar.
Sixty-three Indian nationals, working at the Trishuli-One hydropower project, were also rescued, he said.
The death toll from Wednesday's flash floods in Nepal rose to nearly 580, with more bodies recovered as search and rescue operations continued, according to the latest details shared by Nepalese authorities.
"As far as the number of people (Indians) whom we are not able to contact or who are missing, the figure at this point in time is 320," Jaiswal said.
"There are also around 100 persons of Indian origin who remained uncontactable. These are people of Indian origin who may have gone for Kailash Mansarovar Yatra, but they hold other nationalities," he said.
Jaiswal said 400 Indians were stranded on the Chinese side but were safe.
"They have been in touch with their family. Our embassy has been in touch with several of them. Many of their family members also contacted us through the helpline numbers that our embassy is running in Beijing."
"Our embassy is in touch with local authorities in China, and they are working out as to how these people who are there can be evacuated," he noted.
The MEA also released a photo of 53 Indians who crossed over from China to Nepal. The group includes 37 people from Maharashtra and they have reached Kathmandu.
In a related development, Jaishankar held a high-level meeting with senior officials to review the situation in Nepal, with a focus on tracking the status of missing Indians. India's envoys to Kathmandu and Beijing also joined the meeting virtually.
"Discussed the relief and rescue efforts underway in Nepal today. Our Embassies in Kathmandu and Beijing provided an updated picture in respect of the status and well-being of Indian nationals," Jaishankar said on social media.
"The concerned MEA Divisions apprised us of the further relief supplies to be sent to Nepal. We give highest priority to this issue," he said.
Jaishankar said New Delhi was making "urgent efforts" to ascertain the status and well-being of Indians stuck in flood-hit areas.
Since Wednesday night, India has sent a total of 57.5 tonnes of emergency supplies to Nepal in three military transport aircraft and is in the process of sending more relief materials.
The latest consignment of 10 tonnes of relief materials were sent on Friday evening.
Alongside the relief supplies, India also sent an 11-member team of doctors and paramedics, as well as a reconnaissance crew to assess tunnel rescue operations.
After return of the 21 Indians, Jaishankar said they were very thankful to the Nepalese Army for rescuing them.
"Right now, our effort is on supporting Nepal in the relief and rescue of people. Even today I spoke in the morning to the Nepal foreign minister. We have given them a range of support offers and they are evaluating it," he said.
"Right now, the main thing is that in one place where there is a hydroelectric project, there could be possibility of people who may be in a tunnel. So, we are sending a team to help with the experts," he said.
Jaiswal said India has offered to send Bailey bridges to Nepal along with associated technical teams so that connectivity can be restored quickly in the areas hit by the floods.
"We have also made a specific offer to the Nepal authorities to dispatch NDRF teams along with their associated equipment that can help in ongoing search and rescue operations and bring relief assistance to people impacted by the tragedy," he said.
"We await a response from the government of Nepal on this front. We stand ready to offer any assistance that the Nepal authorities might require," he said.
(With inputs from PTI)