A rise in the dollar exchange rate at special trading this morning was caused by low one-day ruble credit rates on the Russian interbank market, a bank official noted in an interview with RBC. He specified that one-day ruble credit rates reached about 4 or 5 per cent for large banks and 5 or 6 per cent for small and medium-sized banks today. A fall in ruble credit rates started in the afternoon yesterday and it led to a rise in the dollar rate. As a result, the maximum at this morning's trading reached RUR/USD 29.535. The expert forecasted that the average-weighted dollar exchange rate will go up at least 0.02 or 0.03 rubles today.