Today a spokeswoman for the Human Rights Commission said meetings were planned with both networks to discuss the issue.
"We believe this is an accessibility issue as well as a democratic right," she said.
Robinson said TVNZ told them it would not add sign language interpreters because of technical and logistics issues.
An email from the network's chief executive Kevin Kenrick restated TVNZ would not add interpreters to the debates.
TVNZ today confirmed it would meet the Human Rights Commission to discuss the accessibility of the station's election debates.
Mediaworks said it would be working with the Disability Rights Commissioner to discuss ways the network could address the accessibility issue.
"We value their input into the needs of all of our potential audiences and the best ways to improve the situation," said a spokeswoman.
A TVNZ spokeswoman said the network respected the status of sign language as an official language of New Zealand but it would use captioning to meet the needs of hundreds of thousands of deaf and hearing-impaired viewers watching the debates.
"Unfortunately, for logistical reasons, we are not set up to accommodate an interpreter in our live news presentation so sign language won't be incorporated into the televised debates," said the spokeswoman.
The political debates were highly dynamic with quick-fire exchanges, people talking over one another and split-second shifts between camera shots, she said.
"We are not set up to introduce sign language interpreters into an already-complex broadcast environment," she said.
But Robinson said nothing stops the broadcasters from translating the election debates on live television.
"They have effectively done it in the past with Mitre 10 Dream Home. Countries like France often have [an] interpreter on their TV election debates," she said.
He said TVNZ was able to do it but simply refused to.
Robinson said it was important for the country's 20,000-strong deaf community to know what was said in the debates.
It affected every aspect of the deaf community's lives, including housing, education, health, justice, family and employment.
He said the TVNZ refusal reflected the reality of accessibility to services in New Zealand for deaf people.
Robinson said the Human Rights Commissioner Paula Tesoriero had entered discussions talking with TVNZ and Newshub management this week.