Eight of the 19 construction workers from Assam missing for at least 10 days in Arunachal Pradesh have been found by rescue teams but they are not in good health, officials said on Saturday.

Some of the rescued labourers have said three among the remaining 11 had died. The search-and-rescue operation has been scaled up to find the remaining labourers with the deployment of an air force chopper.

The labourers hail from six lower Assam districts and were working on the Border Road Organisation’s Sarli-Huri road project under the Damin circle of Kurung Kumey district, about 90km from the China border and 365km from Arunachal capital Itanagar.

The search for the labourers had started soon after the administration “heard about their flight” on July 13 but they had actually gone missing on July 5, an official said.

Kurung Kumey deputy commissioner N. Bengia and district police chief A. Poswal told The Telegraph that they first found four labourers between 7pm and 8pm on Friday and based on information from them, rescued three of their colleagues around 12.30am. The eighth labourer was found around 5pm on Saturday. The workers had divided themselves into two groups.

“Their condition is bad. They were found by the rescue team near a road close to a forest,” Bengia said, adding that they were “very frail and dehydrated”.

The forest is near the Furak river between Huri and Furak that are 9km apart.

The condition of five labourers is stated to be serious and they have been evacuated in an IAF chopper from Damin to the Tomo Riba Institute of Health and Medical Sciences in Naharlagun under state capital Itanagar. The condition of the eighth labourer was stated to be very serious and he was being taken by road to the district hospital in Koloriang along with two other rescued labourers.

The rescued labourers have told the authorities that two of their colleagues died after falling into a river while another passed away while resting on a stone, Bengia said.

Bengia and Poswal said their first priority was to rescue the remaining labourers. The workers had ostensibly taken the forest route to avoid detection while leaving the camp.

“An IAF chopper joined the rescue efforts on Saturday. Two rounds of aerial survey were conducted by the chopper (from 9.30am to 5pm),” Bengia said, adding that the operation had been hobbled by bad weather.

Bengia and Poswal said they did not have details on how the labourers survived all these days or why they left the camp site or how far they had travelled.

Initially it was believed the labourers fled from the construction site camp because of financial issues or after being denied permission to go home for Id on July 10.

Reports about a body being found in the area on Tuesday fuelled fear and apprehension about the fate of the missing labourers.

Although search by the police and local people did not lead to the recovery of any body, the operation intensified because the area is inhospitable — imposing mountains, stiff cliffs and dense forests infested with poisonous snakes. Mobile connectivity is patchy, which is making the search more difficult.

The district administration sought the help of the NDRF, SDRF and the IAF because of the difficult terrain. A 25-member SDRF team is part of the search party.

“The BRO was getting the project done through a local contractor (from Arunachal) who had engaged sub-contractors for supply of labourers. Of the two sub-contractors from Assam, Raham Ali, is absconding,” Bengia said.

Concern about the labourers has been growing in Assam because of the recent landslide in Noney district of Manipur where 16 of the 61 deceased were from Morigaon district of Assam. They were engaged in the construction of a railway yard at Tupul when the massive landslide struck.

On Friday, Congress MP Gaurav Gogoi and leader of the Opposition in the Assembly Debabrata Saikia wrote to Union defence minister Rajnath Singh urging him to ensure the safety of the labourers.

Seeking an army-led search-and-rescue operations for the labourers from Assam, Gogoi told Rajnath that the workers had been “hired” by a private contractor in Arunachal but there is “no clarity on when, why and how they went missing”.

Twelve of the 26 districts of Arunachal share a 1,080km border with China, which claims the state to be an extension of South Tibet. Reports of people from the bordering districts straying into China are not uncommon.

The labourers, according to a memorandum submitted by the All Assam Minorities Students’ Union (AAMSU) to the Arunachal Pradesh and Assam chief ministers seeking their safety and security, hail from Kamrup, Baksa, Barpeta, Kokrajhar, Bongaigaon and Dhubri districts.

AAMSU general secretary Imtiaz Hussain told this newspaper that they were relieved at the labourers being rescued and hoped the others would be found soon.

“A lot of people from Assam go to Arunachal in search of livelihood. We are much concerned about those working in the neighbouring state,” Hussain said.