"I checked with the Speaker's office and I've had no unauthorised leave of absence from Parliament.
"Every day I've been away has been approved by the Speaker's Office", he told reporters. "I haven't been slacking off in fact I consider myself to be one of the harder working members of this House."
He said Mr Key's remarks were "just a continuation of his petty bickering about my going to South Africa."
Meanwhile, Mr Key's own Chief Whip Louise Upston refused to release records of National Party MPs absences from Parliament.
Instead, she said National had "a robust leave system and I would be very clear if anyone was away without permission and that's what the (new regime) will require public disclosure of."
The only parties to release their attendance records this afternoon were the Greens and NZ First.
A spokesman said the record showed that Green MPs were in attendance for 82 per cent of the hours that Parliament sat during the current Parliamentary term.
Co-leader Metiria Turei said that when Green MPs weren't in Parliament, "they're doing the work the public have asked them to do, they're out with the public at meetings so we're pretty pleased with our result".
A spokesman said Labour didn't believe it was appropriate to release its MPs' attendance records because the leave was often applied "for various personal reasons".
A spokeswoman for NZ First Leader Winston Peters said NZ First had 50 leave applications approved last year. That included applications to leave the House for just half an hour. The spokeswoman said it would take a large amount of time to produce figures giving the exact total number of hours days its MPs were absent.
Mr Peters said that was substantially less than MPs from other parties.
"I don't think we've got a problem at all."
"One of these days if you if you want us to trawl through the whole lot we will, but it's so few in number, about 50 days for all MPs all up which is substantially less than a lot of the MPs, that I don't think we've got a problem at all."