The Palmer United Party will sue Jacqui Lambie and Glenn Lazarus for the millions of dollars it says it spent on getting them elected to federal parliament.

The pair quit PUP, with Senator Lambie this week setting up her own political party.

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Their defections were a betrayal of all PUP members and those who’d voted for the party in Queensland and Tasmania, party director Peter Burke said in a statement on Wednesday.

They had promised to represent PUP for the six-year Senate term if elected, he said.

“Relying on those promises, the party spent millions of dollars and thousands of party supporters worked hard to get Mr Lazarus and Ms Lambie elected,” Mr Burke said.

He says the party has legal advice backing its claim.

The party intends to get back the $2 million it says it spent in Tasmania and $7 million spent in Queensland during the 2013 federal election.

Party leader Clive Palmer was also elected to the Queensland lower house seat of Fairfax.

PUP received more than $28 million in funding, most of it from Mr Palmer’s companies.