Sydney's median asking price for detached houses topped $1 million this week for the first time as sellers raised expectations in a booming market.

The median asking price rose $10,600 over the past seven days, according to Sydney-based data company SQM Research Pty. That's the highest since the firm began reporting the data in April 2009.

Sydney's median asking price jumped $10,600 in a week. Credit:Louise Kennerley

Across Australian state and territory capitals, the median asking price for detached homes jumped $6,400 over the week to $755,100, the figures show.

Record-low central bank interest rates are fuelling a surge in demand from investors, which has regulators concerned that speculative buying is creating an unbalanced housing market.