Singtel Optus has challenged the election watchdog to clarify rules on political donations after it was revealed Telstra did not disclose its purchase of tickets to political party events and fundraisers.

Optus vice president of regulatory and public affairs Andrew Sheridan emailed Australian Electoral Commissioner Tom Rogers suggesting Telstra's approach could mean Optus might not need to lodge its own disclosures.

Optus has written to the government about political disclosure laws.

Telstra claims the payments to political parties do not need to be disclosed because the company derived a commercial benefit greater than the ticket price.

In his letter Mr Sheridan asked for "further clarification around how ... an entity should determine how an attendee at a function or event is getting value equal to the price of ticketed events".