Westpac Bank said it wants to make an all-scrip bid for St George Bank Ltd to form Australia's leading financial services company.

St George said Westpac approached it after the close of business on Friday with the merger proposal, and the two banks have requested that trading in their shares be suspended while discussions continue.

Westpac chief executive Gail Kelly said the merger would create a combined group able to compete more effectively in the Australian market.

'It would create Australia's leading financial institution with regard to meeting customer needs, distribution, strong brands, scale, financial strength and the best products,' Ms Kelly said in a statement.

Ms Kelly, the former chief executive of St George, became chief executive at Westpac at the start of February.

The combined group would have about 10 million customers and would displace National Australia Bank as Australia's largest banking group.

It would have a 25 per cent share of Australia's home loan market and become the nation's largest wealth management group with A$108 billion (S$138 billion) of funds under administration.

'The proposal continues Westpac's focus on Australia and New Zealand and would help Westpac achieve its strategic priorities sooner - building greater strength in distribution and transforming our operations through the integration process,' Ms Kelly said.

Westpac shares closed on Friday at A$25.97, putting the bank's capital at A$48.8 billion while St George closed at A$26.65, giving it a market capitalisation of A$15 billion. -- AFP