MEXICO CITY, Sept 29 (Reuters) - Mexico's central bank raised interest rates by 50 basis points on Thursday, in an effort to counter inflationary pressures, while also flagging possible risks from U.S. monetary policy, the U.S. presidential election and oil prices.

The Banco de Mexico bumped up its key rate to 4.75 percent, as expected by the median forecast of 21 analysts surveyed by Reuters earlier this week.

The bank said the latest move did not herald the start of a monetary policy tightening cycle.

(Reporting by Gabriel Stargardter)