The Prosecutor General's Office said Sariyev, one of the leaders of the Central Asian country's For Reform movement, was detained Monday at Manas airport after checking in for a flight from the capital, Bishkek, to Istanbul.
Prosecutors said $100,000 in undeclared cash was discovered in his luggage. The lawmaker, who has diplomatic immunity, was not placed in custody.
If found guilty of smuggling carried out by an official in abuse of office, Sariyev could face up to 10 years in prison, and his property could be seized.
Sariyev told journalists that he had not declared the cash because he had not been asked to undergo a customs inspection at the airport, but had been led straight to the departure gate. He also contested the sum quoted by prosecutors, saying he was carrying only $10,000, and called the criminal proceedings an attempt to compromise him, due to his political activities.
This is the second smuggling scandal involving an opposition lawmaker in the troubled ex-Soviet republic. In September 2006, For Reform co-chairman Omurbek Tekebayev was seized at a Warsaw airport with half a kilogram of heroin. Polish authorities soon released Tekebayev, deeming the incident a provocation against the opposition leader.