The business, which was founded in 2005 and acts as an online broker between borrowers and individuals willing to offer loans, said it has passed the $1 billion mark after lending 148 million pounds so far this year, up more than 90 percent on the same period of 2013.

Peer-to-peer lenders have become popular among British private investors looking to make more from their money than they could from savings accounts at banks, which are offering lacklustre returns as a result of record-low interest rates. They also attract borrowers by offering lower rates than banks.

"The peer-to-peer industry is growing faster than ever and we’re looking forward to offering new products like ISAs in the near future," Chief Executive and co-founder Giles Andrews said.

(Reporting by Matt Scuffham; Editing by David Goodman)