Three Liberal Party members including two former MPs have been suspended for six months from the party for appearing on a 7.30 investigation into Liberal preselections.

Former federal MP Ross Cameron, former NSW Upper House MP Charlie Lynn and branch member Juris Laucis have been suspended under the party's constitution.

All three are aligned or sympathetic to the once-dominant right faction of the party.

Mr Lynn told 7.30 his suspension was proof the Liberal Party was undemocratic and had abandoned its principles.

"The factions have isolated the membership so there's no democracy in the Liberal Party, and democracy is the key principle of freedom," he said.

He said the suspensions were "disgraceful" and a blight on the party's so-called commitment to individual liberty and freedom of speech.

He said he believed the current pre-selection process was producing candidates favoured by factional bosses rather than the best possible candidates and the party was a breeding ground for "hacks".

"Well, it's a growth of factionalism within the Liberal Party and the factions are very, very strong within the Liberal Party, and if you step outside the factions you are finished forever," Mr Lynn said.

The ABC has obtained the letter sent to Mr Cameron from the NSW Division of the Liberal Party.

The letter states he had been suspended for six months because his comments to 7.30 were likely to cause "damage to the reputation of the division, cause embarrassment to the division or party or parliamentary leader and or reduce the divisions prospect of success in any election".

In the 7.30 story that aired last week Mr Cameron, who held the Federal seat of Parramatta from 1996 to 2004, called the Liberal Party's processes "corrupt".

The six month suspensions given to Mr Cameron, Mr Lynn and Mr Laucis are the maximum allowable and there is no right of appeal.

The decision was made by the Acting State Director, Simon McInnes, in consultation with the party president.

Mr Lynn told 7.30 he does not regret going public about his concerns, and will continue to speak out about the party's processes.

He said Prime Minister Malcolm Turnbull, who famously stated in October 2015 that the Liberal Party was "not run by factions" needed to tell the party to abide by its constitution.

"I would like to think Malcolm (Turnbull) would instruct the party to say, 'we've got to reach out to people who currently can't join the party because the hacks won't allow them to do it'," he said.

"The constitution, their own constitution of the Liberal Party is rorted every time there's a state executive meeting. It's rorted. Now that's a matter of record as well. Malcolm (Turnbull) needs to say, 'look, there's the constitution, let's abide by it and let's encourage people to join'."