The country's seven stand-alone card firms -- Shinhan, KB Kookmin, Woori, Hana, Samsung, Hyundai and Lotte -- extended 20.85 trillion won ($18.5 billion) in the January-March period, up 16.7 percent from a year earlier.
The figure marks a sharp increase from the 2.8 percent on-year gain recorded during the same period a year earlier.
All of the seven credit card companies posted on-year increases in card loans during the six-month period, with Woori Card posting the biggest rise of 28 percent.
Hyundai came next with 23.6 percent, followed by Hana with 20.3 percent and Samsung with 19.5 percent. KB Kookmin was the sole credit issuer to register a single-digit growth rate with 5.5 percent.
Market watchers attributed the sharp first-half increase to local banks' stricter loan screenings in line with the government's push to rein in soaring apartment prices.
Also responsible were credit card issuers' efforts to jack up card loans to offset falling income due to a government decision to cut credit card fees for small merchants, they said.
"Tougher bank loan rules led to the increase in card loans," an industry source said. "In addition, credit card companies pushed to extend more card loans in a bid to cope with falling profitability."
However, the amount of credit-card loans is expected to shrink in the second half of the year from the first six months due to financial authorities' move to regulate total lending, he added.
Eight stand-alone credit card companies chalked up a combined net profit of 966.9 billion won in the first half of the year, down 32 percent from a year earlier. (Yonhap)