Many restaurants are still failing to serve fresh food or healthy choices to children - and price is no guarantee of quality, campaigners have found.

Children's menus were found to include potatoes pre-mashed in Holland, fish fingers pre-cooked in Poland and a chicken product with 19 additional ingredients produced variously in Kazakhstan, Russia, Vietnam, Argentina, Malaysia, India, Singapore, Indonesia, China, Ukraine and Slovakia, according to the Soil Association.

The study of 21 of the UK's most popular restaurant chains found significant improvements made by a small number of chains, but "continuing widespread poor practice with many restaurants failing to serve fresh food or healthy choices".

The majority of chains were not freshly preparing and cooking the majority of their food - more than half gave no indication of where their food came from and just one chain, Jamie's Italian, could reliably tell parents where their meat came from.

Cafe Rouge, Frankie & Benny's and Pizza Hut still offer children free or discounted refills of high calorie sugary drinks as standard, the Soil Association reported.

However, 10 of the chains are serving a portion of vegetables or salad with every meal, up from six chains in 2013, and nine include information on the menu about the origin of ingredients, up from five previously.

Angela Mitchell from Soil Association Scotland said; “‘Our 2015 league table includes big winners and big losers - adults expect to be offered real food and real choices in restaurants and we think children deserve the same.

"We’ve found some up-market eateries are designing menus that make healthy eating for children almost impossible, and price is no guarantee of quality - lower cost restaurants are outperforming more expensive chains.

"Since our first league table Harvester and Prezzo have proved it’s possible to make major improvements – we’re now calling on other restaurants to raise the bar and give our kids the food they deserve.”

Jamie Oliver's Jamie's Italian, which has two eateries in Glasgow and Edinburgh, topped the table with a score of 64 out of 80, up from 50 two years ago, and Prezzo was the biggest climber, moving up 13 places to sixth position.

Strada, KFC and Burger King were the three worst scorers, on 25, 21 and 11 respectively.

A survey in 2013 for the Soil Association found 40per cent of parents eat out with their children at least once a fortnight, but 66per cent of parents do not believe children's food in restaurants is good enough.

Anya Hart Dyke, one of the parents who reviewed restaurants in Scotland said: “It’s pretty stressful taking your child to a restaurant as it is - will there be room for the buggy? Will they have high chairs? Will I get a chance to eat my own meal or have to get take-out again? The last thing you expect to worry about is the food. What I feed my child is the single-most important consideration for me as a parent, after keeping her safe. It astounds me that for example one restaurant offered baked beans heavy with sugar and salt as an alternative accompaniment to vegetables, while the adult menu is often a great deal healthier.”

Soil Association spokesman Rob Percival said: "We've found some up-market eateries are designing menus that make healthy eating for children almost impossible, and price is no guarantee of quality - lower cost restaurants are outperforming more expensive chains."

Cafe Rouge brand director Georgia Hall said: "While we don't offer free or unlimited refills, we do offer refills for 75p on our choices of drinks for children, which include fruit juices, milk and cordials.

"In light of the debate over fizzy drinks, we will be reviewing this offer and indeed all of our kids' choices as we create our next menu in time for Christmas.

"We should highlight that our children's starters contain one portion of their five-a-day, as do three of our main courses and one of our desserts."

The survey was carried out as part of the Soil Association Scotland's Out to Lunch campaign.