South African media group Naspers has signed an increased $1.6 billion forward start loan with a group of international banks, banking sources said on Friday.

The forward start extends the maturity of Nasper's existing loans to 2013 from 2011 and re-denominates the currency from sterling to U.S. dollars.

Forward start loans allow borrowers to lock in loans ahead of maturity in return for increased margins and fees.

The financing was launched at $800 million but was doubled to $1.6 billion after receiving strong support from the market and more than 20 international banks joined the deal, the sources said.

Lenders' commitments were scaled back despite the increase, one of the sources added.

The facility -- which was arranged by initial mandated lead arrangers and bookrunners Barclays, Citigroup, Nedbank and Standard Bank -- pays a margin of 350 basis points over LIBOR on drawn amounts and a commitment fee of 140 bps or 40 percent of the margin on undrawn commitments.

The new loan will replace a three-year 700 million pounds ($1.16 billion) loan that was used to back the acquisition of UK internet auction firm Tradus that will mature in 2011.

(Reporting by Alasdair Reilly)