Fairfax newspapers say documents obtained by WikiLeaks show Mr Garrett’s former chief of staff, David Williams, told the US Australia could accept a deal.
The agreement would have overturned the ban on commercial whaling, in return for Japan reducing its so-called scientific research program.
The deal had the backing of New Zealand and the US in the lead-up to International Whaling Commission talks in the middle of last year.
The documents also show Mr Garrett believed he was more committed to ending whaling than the Australian Government officials who were negotiating with Japan.
Mr Garrett’s office has been contacted for comment.
The latest US diplomatic cables released by WikiLeaks also show Japanese and US officials discussed ways of reining in the militant anti-whaling group Sea Shepherd.
Sea Shepherd has been successful in hampering Japanese whalers during the annual Antarctic hunt.
The cables reveal the US envoy to the International Whaling Commission, Monica Medina, held talks with the head of Japan’s fisheries agency, Katsuhiro Machida, in late 2009.
Read the rest of the story: Australia, Japan in secret talks on whaling deal.