Australian shares are weaker as details of the Federal budget deficit blowout become clear.

The benchmark All Ordinaries index closed  down 0.62 per cent to 5164.6 and the Australian dollar is down US.23c  to US82.49 per cent.

•Treasurer has explaining to do on budget
•Budget deficits to nearly double

The weakness follows declines on foreign markets over the weekend with the US Dow Jones industrial average down 1.8 per cent to 17280.83 and the UK FTSE index down 2.5 per cent to 6300.63.

News on the American economy was positive with the consumer confidence index rising to 93.8 from 88.8.

Oil slumped on Friday to fresh 5-year lows, and the International Energy Agency slashed its global demand outlook for 2015 by 230,000 barrels to 900,000 barrels. Brent crude prices were down by $US1.83 t to $US61.85 a barrel.

Most base metal prices were stronger but aluminium, iron ore and zinc weakened. Gold fell 0.3 per cent to $US1222.20 an ounce.

BHP Billiton shares are down 13c to $28.33, Westpac bank fell 23c to $31.82 , Woolworth’s is down 66c to $29.20and Telstra is up 4 cents to $5.74.