Many people are taking out balance transfer credit cards but not repaying the debt they owe.
Mining shares surge boosts FTSE
The FTSE closed nearly 43 points higher at 6286
Mining stocks helped the London market end a five-day losing streak as bargain-hunters returned to boost the FTSE 100 Index.
The FTSE 100 ended up 42.9 points higher at 6286.6, as investors shrugged off concerns over weakness in the American and Chinese economies.
Weaker-than-expected Chinese growth this week spooked markets, while soft economic data from the US and further cracks in the eurozone also underlined the fragile global recovery. That has driven commodity prices sharply lower as traders bet on weaker demand.
The International Monetary Fund this week cut its world growth forecast for 2013 to 3.3% from 3.5% and warned that the "main challenge is very much in Europe". But with officials from the world's 20 economic powerhouses meeting in Washington to search for ways to remedy sluggish global growth, investors saw an entry point.
Rebecca O'Keeffe, head of investment at Interactive Investor, said: "Equity markets are beginning to stabilise after experiencing a modest correction this week. Markets were undermined by the prospect of weaker economic conditions in both the US and China, and this will remain the focus in coming weeks."
The Dax in Frankfurt ended marginally lower but the Cac 40 in Paris was up more than 1%. A rare earnings miss for IBM edged the Dow Jones Industrial Average lower.
On the currency markets, sterling was 0.2% down against the dollar at 1.52 and 0.3% down against the euro at 1.17. Gold managed to return above the psychological threshold of 1400 dollars an ounce, after heavy falls earlier this week.
Eurasian Natural Resources - the biggest faller on Thursday - was the strongest gainer on Friday, surging 27% or 61.2p to 291p, as major shareholder Alexander Machkevitch said he is considering a takeover bid for the Kazakh miner. Fellow miner Fresnillo was up 31p to 1117p, a 2.9% gain.
Banks also fared well with HSBC leading the sector higher with a 15.9p gain to 679.2p.
The biggest risers on the FTSE 100 were Eurasian Natural Resources up 61.2p to 291p, Vedanta Resources up 66p to 1151p, Evraz 5.4p higher to 161.8p and Fresnillo up 31p to 1117p. The biggest fallers on the FTSE 100 were IMI 19p lower to 1174p, Wolseley 32p weaker at 3133p, Rolls-Royce 9p lower at 1123p and Tesco 2.5p off at 363p.