Sydney - Westpac Banking Corporation, one of Australia's Big Four high street banks, is in merger talks with fifth-placed St George Bank, and a marriage would create Australia's largest financial services company, Westpac said Monday.

Shares of both banks were placed in a trading halt with an announcement expected Tuesday.

"This would lower risk and costs for St George, and position the combined business to withstand challenging funding markets and take advantage of opportunities created by the dislocation in capital markets," Westpac chief executive Gail Kelly said.

"For customers, it would make it more convenient to access customer touchpoints, including the largest distribution network with over 1,200 branches and in-stores as well as more than 2,700 ATMs."

In February, South African-born Kelly left the top job at St George to take charge at Westpac. She is the first woman to head an Australian bank and the only woman in charge at any of Australia's top 20 listed companies.

Kelly, 52, is the second South African to head a top 20 Australian company, following the elevation of Marius Kloppers to chief executive of giant miner BHP Billiton in May.

Kelly, a former schoolteacher, arrived in Australia in 1997 and was appointed managing director of St George in 2002.

"I've got lots of energy," Kelly said in a recent magazine interview. "I don't waste time. I move. I finish things. I don't try and do things to the nth degree. I now what's important and what's not."

The government has banned mergers among the four major banks: Westpac, National Australia Bank, ANZ Banking Corporation and Commonwealth Bank. (dpa)