Actress Isla Fisher has shared a sweet tribute to her close friend and former Home And Away co-star Kate Ritchie.

On Thursday, Fisher posted a series of photos on her Instagram story to celebrate the radio host turning 47.

“Happy Birthday to the most beautiful soul inside and out! I (heart emoji) you!,” Fisher wrote alongside a throwback picture titled “31 years of friendship”.

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Fisher and Ritchie starred alongside each other on Seven Network’s beloved soap Home And Away more than three decades ago.

Fisher played Shannon Reed from 1994 to 1997 and Ritchie played Sally Fletcher from 1988 to 2008, with a brief reappearance in 2013.

The two have remained close friends since first meeting on the show, with the pair often documenting their catch-ups when they’re in the same country.

In December, Ritchie flew to London — where Fisher currently lives — for a special Christmas reunion.

“I’m really good friends with lots of Aussies,” Fisher told 9honey at the time.

“I love Kate Ritchie.”

The former TV star returned to the airwaves on August 8, following a six-month mental health break from her Nova radio show Fitzy & Wippa with Kate Ritchie.

Ritchie had announced in February she was taking a break from the show.

At the time, The Daily Mail had published photos of Ritchie on the phone looking distressed. The mum-of-one called out the paparazzi for invading her privacy, bravely revealing the toll it had taken on her health.

Speaking on-air about her return, Ritchie revealed she was overcome with gratitude by all of the support she has received.

“The amount of people who have reached out to me over this period of time, and since earlier in the year, has been absolutely mind-blowing,” Ritchie said.

“So if you’re listening and you were one of those people that reached out, or stopped me in the street.

“Or even just smiled at me over the tomatoes in Harris Farm.

“For people to bother to actually say, without being intrusive, ‘Hey, it’s really nice to see you, hope you’re doing well. I can’t wait to hear you back on the radio’ ...

“Thank you for bothering, because I read all of those messages and they made all the difference.”

Ritchie added kindness is what kept her going during this challenging time.

“Despite all of the support and the love I feel, I didn’t do it for anyone else — I did it for me,” Ritchie shared.