But he said the onus was on the party, not the donor, to ensure the rules were followed. Ross said it was several smaller lots of money that added up to $100,000.
Bridges earlier said he is confident his hands are clean and it is the party that has questions to answer.
And he added that he had no concerns about the party as he believed it had good processes to deal with political donations.
Ross, who quit and was kicked out of the National caucus last year, lodged a complaint with police about what he alleged was a $100,000 donation to the National Party from businessman Yikun Zhang that was then split into smaller amounts to hide it.
Bridges has strongly denied that, as has the National Party hierarchy which has said the $100,000 sum cited by Ross was made up of eight separate donations from different donors.
There is no suggestion of any wrongdoing by Zhang.
Ross alleged Bridges, MP Todd McClay and party general manager Greg Hamilton all knew about the donation being split up.
National Party leader Simon Bridges has denied any wrongdoing over donations. Photo / Mark Mitchell.
"Simon asked me to collect this donation. He was at pains to point out the donation should not be made public and could I ensure this," Ross said last year of the donation.
Ross said he did as Bridges asked, splitting the money into chunks smaller than the $15,000 limit at which donations had to be declared.
But Bridges told reporters this morning he had not instructed anyone to break up the $100,000 donation, nor has he said anything that could have been interpreted that way.
He said the matter seemed to have nothing to do with him, and he was completely confident his hands were clean.
"I've seen the statement (from police). On the face of it, it seems to be about the National Party. The SFO is investigating. I think there's questions for them to answer and you'd hope in due course they'll do that.
"I expect the National Party to fully cooperate."
He was not going to seek clarification from the SFO that he was not involved.
"I would have expected, if that was the case, that they would have been in contact. They haven't."
He did not have concerns about the National Party as he believed the donation had been handled lawfully.
A spokesman for the National Party said neither president Peter Goodfellow nor Hamilton had any comment at this stage.
Ross has not responded to requests for comment so far today.
Last October Ross had a two-hour meeting with police during which he played a recording of a conversation between Bridges and himself.
He released the phone recording along with text messages between him and Hamilton, but Otago Law Professor and electoral law expert Andrew Geddis said that these did not show anything concretely illegal.
Geddis said there were several reasons why the Police might have referred the case - and several areas in which wrongdoing could have taken place.
He said the referral itself did not mean the SFO would investigate - it was SFO procedure to assess any such referral and decide for itself whether it warranted further investigation and fell within its ambit.
Geddis said police could have referred it because it was too complex for them to assess whether there had been wrongdoing and they wanted the SFO to analyse it.
It was also possible that the police had uncovered something suspect and wanted the SFO to look into it. The SFO had greater, and quicker, powers to compel the handover of information required.
If that was the case, Geddis said there were several areas in which alleged wrongdoing could have occurred - and not only by the National Party.
One possibility was if somebody had made up false donor names and addresses to split the donation up.
"If it turns out the donations were given under false names or in ways that mean the party was misled as to who they actually came from, then there are a range of potential offences under the Electoral Act that were committed by the person who disguised their identities.
"In other words, the person who gave the donation under a false identity will have potentially committed offences."
He said some of those were very serious and punishable by up to two years' imprisonment.
"There is then a secondary question as to whether anyone within the party apparatus - whether it be Simon Bridges, Jami-Lee Ross or any of the party administration - were either complicit in someone hiding their identity or allowed the donations to be made knowing this has happened. In which case they would be party to any action under the Electoral Act."
The text messages released by Ross showed Hamilton asking Ross for more information about the donors, saying the addresses Ross provided did not match up with the electoral rolls.
In response, Ross says he had simply passed on the names and addresses he was given and did not know the individual donors himself.
Geddis said the text messages appeared to show Hamilton trying to sort out the identities of those donors.
If the party had not been able to connect the donation to an actual person, the donation should have been treated as anonymous and any sums of more than $1500 returned to the Electoral Commission.
Parties must keep records of all donations of more than $1500 and must publicly declare all those of more than $15,000.
There is no public evidence Bridges asked for the donation to be split up as Ross has claimed.
A recorded phone call released by Ross includes Ross asking Bridges what to do with the donation and saying it "meets the requirements where it is under the particular disclosure level because it's a big association and there's lots of people and multiple people make donations — so that's all fine."
Under the Electoral Act, the general secretary is personally held liable for illegal or corrupt practices involving party donations returns.
