Douglas Amobiok Oroigwe, 29, and Julius Festus Chijelwu, 24, both Nigerian nationals, and their Nepalese accomplices Sneha Shrestha, 21, and Keshav Gurung, 21 were arrested from Lalitpur and Kathmandu districts on Tuesday, they said.
Oroigwe and Chijekwu, who arrived in Nepal in July on visit visas, befriended Sneha and Keshav and began cheating people, the police said.
In one such incident, the two Nigerians hacked the email account of trekking agent Mingmar Lama, and asked German national Armin Otto Riegr, who was looking to visit Nepal, to send USD 1,980 posing themselves as Lama.
The gang created a Facebook ID called 'Mirable Wilson' impersonating a US Army officer and befriended Amrit Dahal, 24, a Nepali Army soldier and "asked him to send USD 6,890 to the bank account of Shrestha and Gurung," police said.
They have also duped a French and a German national in separate cases by promising them help in their Nepal visit.
According to preliminary investigations, they defrauded many people of millions of rupees by hacking into email accounts and befriending the victims on Facebook, the police added.