Asiatic cheetahs, a subspecies of the fastest animal on earth, are extinct everywhere except in Iran, where they are considered to be critically endangered. But marking a rare success, conservationists at the Persian wildlife heritage foundation (PWHF) have spotted a group of five Asiatic cheetahs (also known as Iranian cheetahs) – a mother with four cubs.

Four wildlife experts from the PWHF saw the family group at the weekend as they were returning from a field trip in Iran's Turan national park, home to some of the largest populations of Asiatic cheetahs in the world.

"They could not believe what they were seeing ," Delaram Ashayeri, project manager at PWHF, told the Guardian. "They took out their camera and filmed it." The picture showing the five cheetahs, with four of them are looking directly into the camera, has since been shared repeatedly by Iran's huge online community.

The discovery comes after a decade-long campaign in Iran to protect the cheetahs from extinction and raise awarness, especially among indigenous people living close to their natural habitat.

"In the past year or so that we closely monitored Turan, we never spotted a family, especially female cheetahs with cubs," Ashayeri said. "It shows Asiatic cheetahs are surviving, breeding cubs are managing to continue life. It's good news against a barrage of bad news about these animals."

The conservation of Asiatic cheetah project (CACP), an initiative between Iran's department of environment and UN development programme, has led to at least 14 reserve areas being set up, mainly in central Iran, in Yazd, Semnan and Kerman.A number of NGOs, including PWHF and the Iranian Cheetah Society (ICS) have also stepped in to help.

Morteza Eslami, the ICS's head, echoed Ashayeri, saying the recent filming showed conservationists in the country were on the right path.

"Something that people rarely knew about a decade ago has now became a national cause for concern," he said. "When we spoke about Asiatic cheetahs in the beginning, people used to ask if we in Iran had any cheetahs. Now they are asking how many are left." Earlier this year, the reformist Shargh daily reported that a group of 46 prominent artists, including the celebrated film-maker Abbas Kiarostami, had opened an exhibition aimed at raising funds for conserving the animals.

An average of 1.5 cheetahs used to be killed in Bafgh in the city of Yazd every year, Eslami said, whereas this number has been reduced to almost zero.

Research conducted by the ICS and released recently suggested there were 40 to 70 cheetahs in Iran.

International funds and equipment have been vital to the Iranian NGOs but blanket sanctions imposed on the country by the west over its nuclear programme have affected environmentalists, who have struggled to get international funding.

"Unfortunately, due to sanctions, we have not been able to reach international funds," Eslami said. "We are an NGO, we are independent of the government but due to sanctions we had serious difficulties in obtaining camera traps, for example. It is not possible to directly buy them and we have to go through a number of intermediaries and that means that we have to pay more to get our hands on them. Also, we have banking restrictions, making it difficult for us to pay for these camera traps."

Despite the recent success, Eslami warned that a number of road construction and mining plans close to reserve areas had put the campaign at risk.

"These road constructions and mines are seriously endangering and undermining our work and could lead to the extinction of Asiatic cheetahs in Iran," he said. "We hope that the Iranian government halts these projects as soon as possible."