The prices of long-term government securities rose by 15-20 paise today amid thin trading, while the call money rates remained in the range of 6.25 per cent to 6.50 per cent.The government security prices opened almost at Wednesday's closing levels and went up during the later part of trading hours. Market dealers said the rally, which did not continue for long, was mainly liquidity driven.A dealer with a private sector bank said, "Through its repeated OMOs, the Reserve Bank of India has signalled that the yields were already at low levels. On this concern, the prices did not go up too much.""The cut-off yield of 7.43 per cent set for the 9-year paper gave the market a feeling that the yield of 10-year paper should have been around 7.50 per cent "" currently it is at 7.25 per cent. This implies that the market expects the prices to be lower than what they were today. This is the basic reason why the morning rally was halted," another dealer said.At its repo window, the central bank continued to mop up huge liquidity from the market. It received 7 bids of Rs 9,480 crore, which were accepted at a cut-off rate of 6 per cent. There was no bid for one-day reverse repo auction.In the call money market, easy liquidity kept the rates soft. The overnight rates opened in the range of 6.25 per cent to 6.50 per cent and remained in that range throughout the day.Government security prices are likely to remain stable with an upward bias on Friday. Dealers said liquidity will favour the prices to go up, but added that market participants will remain cautious after the recent spate of auctions.Call money rates will continue to remain soft and will remain between 6.20 per cent and 6.50 per cent.