Border Security Force (BSF) trooper Satyasheel Yadav was part of a water patrol party in Akhnoor area of the international border in Jammu and Kashmir.
He was swept away in the river after their motor boat developed a mechanical fault on Wednesday, BSF sources told IANS here.
"While three of his colleagues managed to swim to safety, Yadav was carried to the Pakistani side by the powerful currents of the river.
"Pakistan Rangers have confirmed that the trooper is in their custody. We have sought a flag meeting to get the trooper back," a BSF source added.
The accident carried the trooper to Bajwaat village in Sialkot area of the Pakistani side.
Yadav hails from Ferozabad in Uttar Pradesh.