Robert Irwin and his mother Terri Irwin are known to be very close. 

On Monday, the mother and son duo posed together in multiple images shared to Instagram during their travels overseas in May. 

In two of the photos, Terri, 59, and her son, 20, were pictured together, beaming for the camera. 

And some detractors complained that the pair are frequently seen together. 

'Is Robert and his mother joined at the hip. She is in every pic you see of him,' one person wrote in the comments while another said, 'He's 20 now!'

However there was plenty of support for their close relationship, with one person replying, 'He's a lucky young man to have her.'

Another wrote: 'People saying why Robert has he's mum in so many photos. Remember every day is precious. Life is fragile. The Irwin's like millions of other families have experienced loss on a monumental scale.

'Steve was larger than life. It's lovely that they do spend so much time with each other. Don't be so critical.'

One more said: 'What is wrong with someone having a close relationship with their mother?'

'Who cares? It's his mom and they seem to be a very tight-knit family,' yet another said. 

The pair did nothing to dispel talk about their closeness when they stepped out together in Oregon earlier this week. 

The mum and son were in the region visiting family members and appeared in great spirits as they strolled together.  

It comes after an I'm A Celebrity... Get Me Out Of Here! producer expressed concerns about host Robert's decision to bring his protective mother Terri on set. 

Terri accompanied her son on his trip to South Africa as he films his debut season of the popular Channel 10 program alongside co-host Julia Morris, 55. 

Speaking exclusively to Daily Mail Australia, an anonymous producer has admitted that Terri's presence on set every day is 'a little creepy', saying: 'It is giving 'bringing your-mum-to-school-camp vibes.'

Terri, who has been in charge of Robert and his big sister Bindi's showbiz careers since the death of their father Steve in 2006, has apparently kept a close eye on everything Robert does while working on the program. 

'The two have an excellent relationship and Terri couldn't be nicer but there are not many situations where employees will have their mum at work with them, just to make sure everything is above board,' the insider said. 

Comparing Terri to the Kardashians' famous 'momager' Kris Jenner, the producer claimed Robert Irwin's contract even included a section that allowed him to bring his family on set. 

'The deal was done when Robert signed on as host late last year. He wanted his family to come with him,' they alleged, adding: 'Maybe it will be just for this series,  but maybe Terri will always be standing in the wings. Who knows'. 

Robert previously confirmed that the entire Irwin clan would be joining him in South Africa, telling The Daily Telegraph in January: 'I've got everyone, including my little niece Grace, coming over, so the whole family are there'. 

While Terri is said to be 'in her element' watching Robert win over audiences on the show, the producer cast some doubts about the zookeeper's protective attitude - especially when it comes to her son's dating life. 

Robert recently split from girlfriend Rorie Buckey after nearly two years of dating, with reports claiming Terri's opinions of the relationship may have contributed to the break-up. 

'The rumour on set is that Robert has been withholding information from his mum on his dating life, which is pretty standard for most 20 year old boys,' the source spilled, claiming that 'cracks will continue to appear' if Terri continues to get involved in his love life.

It comes after reports surfaced claiming Bindi has urged Terri to let Robert 'live his life' following his split from Rorie in February. 

According to Woman's Day, Bindi has rallied around to support her brother as he navigates the break-up by himself, and is said to have 'unbreakable loyalty' towards him.