Police in the northern Thai Binh Province took him as he arrived in Hanoi's Noi Bai Airport, and will investigate him for extortion.
They also raided his office and carried out an hours-long search.
The arrest follows an investigation into a man named Pham Minh Cuong, 37, for extracting protection money from businesses mining sand in tidal flats in Thai Binh that borders Hanoi.
Cuong told authorities he forced them to pay up based on the amount of sand they mine or to sell to him at low prices.
In this manner, Cuong’s gang earned billions of dong between 2020 and 2022. (VND1 billion = US$41,150)
Nhuong, 60, holds a Ph.D in economic law. He was appointed the deputy head of the People’s Aspirations Committee in September 2018.
His connection with Cuong's racket has not been revealed.