Simon Bridges' mum says he 'wasn't brought up' to swear

Another MP's mum has waded into the National Party omni-crisis, but this time to say she's disappointed in her offspring.

National Party leader Simon Bridges' mother Ruth told NZME she didn't want to hear her son using "bad language".

"He certainly wasn't brought up that way, but I suppose he was trying to be blokey amongst the blokes."

Mr Bridges was recorded by rogue former National MP Jami-Lee Ross as calling another MP, Maureen Pugh, "f**king useless".

He apologised to Ms Pugh, who accepted his remorse. But that didn't stop her mum from getting stuck into Mr Bridges, calling him a "dumb-arse" and telling him to go "suck eggs".

Ms Bridges, 80, told NZME it hurts to read mean things about her son.

"They love to say things like 'Simple Simon', 'you're a Muppet'. It's upsetting and you feel the pain but you get numb to it. There's nothing you can do about it."

When she texted Mr Bridges earlier in the week to check in on her son, he reportedly told his mother he didn't need her advice.

She's confident he'll lead the party into the 2020 election, saying the recordings released so far are probably the most damaging Mr Ross has.