BEIJING, Jan 18 (Reuters) - Chinese spot steel prices dipped 0.3 percent over last week, with traders concerned about the impact of tighter monetary policies on the property market, according to industry consultancy Mysteel. Mysteel's composite price index fell to 146.9 points, the first decline in over a month, with prices of long products -- used primarily in construction -- dropping 0.8 percent during the week. Prices of flat products used in automobiles and household goods still rose 0.1 percent over the period. The steel market is still digesting the decision last week by China's central bank to raise the country's bank reserve ratio, which could result in a construction slowdown. Traders were less concerned by leading steel maker Baosteel's decision to abandon planned price rises for February, saying the move had more to do with upcoming benchmark iron ore price negotiations than any underlying weaknesses in the market. Iron ore prices on the domestic market continued to rise last week, with Mysteel's composite index up 5.6 percent to 128.9 points, its highest since October 2008. Ores produced at Chinese mines rose by 6.8 percent over the week, suggesting that the increase in prices over the last month has made lower-quality domestic reserves more economical to produce.