Telemarketers working on behalf of EnergyAustralia signed customers to new plans without their consent, the consumer watchdog alleges.

The Australian Competition and Consumer Commission is taking the company and a telemarketing contractor to the Federal Court for breaching consumer laws.

The watchdog says telemarketers at the firm Bright Choice told people they would be sent information to help them decide if they wanted to sign up to gas and electricity plans.

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They then allegedly went ahead and signed them up anyway. EnergyAustralia mailed them welcome packs containing contracts and treated them as new customers.

The allegations emerged from a joint investigation by the ACCC and the Australian Energy Regulator, which has instituted separate proceedings against EnergyAustralia.

It comes after the company agreed to pay a $1.2 million penalty in April over the deceptive conduct of some of its door-to-door salespeople.

“Energy companies must act to ensure their sales agents and representatives do not engage in unlawful sales tactics,” ACCC Chairman Rod Sims said on Friday.

EnergyAustralia says it terminated its contract with Bright Choice in September 2013 after it learnt of the dodgy sales tactics.

“The conduct occurred without EnergyAustralia’s knowledge and was in contravention of our contractual, training and scripting requirements with them,” the company said in a statement.

The firm says it reported the matter to the ACCC and AER, and has since contacted wronged customers and boosted training and compliance measures.