Treasurer Scott Morrison has launched an extraordinary attack on the economic credentials of Labor byelection candidate Kristina Keneally in front of 300 business leaders, while trashing the economic legacy of the Labor government in its handling of the global financial crisis.

In an annual keynote economic speech, Mr Morrison described the former NSW premier as "scandal plagued", saying she promoted ministers who ended up in prison and "dragged the economy to the bottom of the pack".

Treasurer Scott Morrison Credit:Alex Ellinghausen

He warned a victory for Ms Keneally in the Bennelong byelection could end with the "lunacy, failure and economic mismanagement" of a Shorten Labor government.

Figures from the Australian Bureau of Statistics showed the NSW economy continued to grow, though at a slower rate than the nation as a whole during Ms Keneally's time in office from 2009-2011.