The Queensland-based Heritage Bank has complained to the ALP about one of its election slogans.

Opposition Leader Bill Shorten and Labor have been using the phrase "putting people first" on the campaign trail, while the customer-owned bank's trademarked brand slogan is "people first".

Heritage's head of banking operations David Janetzki is running as the Liberal National Party's candidate in the upcoming Toowoomba South state by-election.

A spokesman for Heritage Bank told the ABC it had written to the ALP to point out the similarity between the two phrases and asked the party to be careful in how it was used.

Federal Opposition Leader Bill Shorten has defended the use of the slogan and is standing his ground.

"The Labor Party's been putting people first for 120 years," he said.

"It's the idea upon which that Labor Party was formed.

"We are the party of the middle class and working class families and individuals of Australian society."

Shadow attorney-general Mark Dreyfus questioned why Heritage Bank could take issue.

"This is a very curious claim, which may have more to do with the LNP connections of a senior officer of the Heritage Bank," he said.

"I can't imagine many Australians would confuse the Heritage Bank with the Australian Labor Party."

Heritage Bank said the slogan had been trademarked since 2007.

CEO Peter Lock said the bank wanted to protect "its much-loved motto", and had "absolutely no political motivations".

"As an organisation, we are absolutely apolitical and we don't seek or have any interest in being involved in the election campaign," he said in a statement.

"That's why we feel it is important for our customers that we make the distinction between the political slogan and what Heritage Bank stands for."

Mr Lock added that Heritage did not endorse the political inclinations of individual staff members.