UPDATE 1-Telefonica sees swift Brazil approval for GVT bid

* Telefonica offers to buy GVT in cash

* Deal may require approval only by telecom regulator

* GVT management could be invited to stay-official (Recasts, adds byline, comments)

By Guillermo Parra-Bernal

SAO PAULO, Oct 7 (Reuters) - Spain's Telefonica (TEF.MC) offered to pay in cash for Brazil-based GVT GVTT3.SA on Wednesday, adding it does not expect a lengthy regulatory process.

The deal, which Telefonica valued at 6.5 billion reais ($3.7 billion) in cash, aims at buying at least 51 percent control of the Brazilian telecommunications company, investor relations director Gilmar Camurra said in a conference call.

The fact that Telefonica's Telesp unit and GVT have no "geographical overlap" would pave the way for swift approval, Camurra and other executives at Telesp said.

"The combination makes sense because there is a perfect geographical fit. It is a complementary business model, because financially we could grow and generate cash," Camurra said.

The offer is to buy GVT shares at 48 reais each, meeting a poison pill clause that is in GVT statutes, Camurra said. Telefonica aims to control 100 percent of GVT, he said.

GVT's management could be invited to stay if the bid succeeds, the executives said. ($1=1.756 reais) (Reporting by Guillermo Parra-Bernal, editing by Leslie Gevirtz)