Animal welfare campaigners have criticised Edinburgh\'s Zoo\'s latest exhibit saying the pandas are just a \"primarily commercial deal\". Two charities, CAPS and the Born Free Foundation, said they were concerned for the pandas\' welfare following years of \"problems\" at the zoo. Tian Tian and Yang Guang are set to arrive at the zoo from China on Sunday. An Edinburgh Zoo spokesman said it was run by a registered charity and nothing it did was \"commercial\". Edinburgh Zoo, which is run by the Royal Zoological Society of Scotland, is to pay $1m (£600,000) to the Chinese authorities each year for the pandas, which are due to stay at the zoo for at least 10 years. Visitor numbers at the zoo are expected to rise by 70% in the first year of the pandas arriving. It is then understood the visitor numbers will rise again if they have cubs. It was reported last year that about 60,000 fewer people visited the zoo in 2009 - 10% down on the previous year. The fall in numbers reportedly cost the zoo about £1m. It closed its exotic bird enclosure, Rainbow Landings, and started to charge members for parking. The same year, the zoo also said it may need to downsize after plans to sell off land for housing to raise cash were rejected. Chris Draper, Born Free Foundation\'s senior animal welfare scientist, said of the panda deal: \"This is a short-sighted and retrograde step. \"Over time, I suspect we will see that this has less to do with conservation or education, and much more to do with resurrecting the fortunes of a fading visitor attraction. \"Tian Tian and Yang Guang are not \'flagships\', nor even diplomatic gifts, but commodities in a primarily commercial exchange.\" Liz Tyson, director of CAPS (Captive Animals\' Protection Society), said there was already a question mark over the zoo\'s ability to meet acceptable standards. She said: \"To introduce the pandas into the equation is not only a backwards step in terms of conservation and ethics, but the cost that comes with them means that the zoo is putting extra pressure on their finances when they should be focusing on ensuring they meet the most basic standards for the animals already there.\"In short, it doesn\'t bode well.\" Born in 2003, Tian Tian (meaning \"sweetie\") and Yang Guang (meaning \"sunshine\") will be under custodianship of the Royal Zoological Society of Scotland (RZSS). Tian Tian and Yang Guang will make the journey from China in perspex cages on board a special chartered flight on Sunday. They will be the first pandas to live in the UK for 17 years. The pandas, who will live in separate enclosures, will be given about two weeks to become accustomed to their new environment before they go on display to the public. Their £250,000 enclosures each contain a water feature, cave and climbing structures made from tree trunks. An Edinburgh Zoo spokesman said: \"Edinburgh Zoo has designed and built the best enclosures in the world, which are specifically designed to suit all the pandas\' requirements. \"We have world-class expertise including our keepers and our vets to oversee the pandas\' welfare. \"Edinburgh Zoo and Edinburgh are centres of excellence for biosciences and animal welfare and the zoo is a world leader in breeding animals which are difficult to breed. \"Scotland has an ideal climate with the temperature almost identical this weekend to China right now. \"Nothing that the Royal Zoological Society does is commercial because it is a registered charity. \"Its objectives set up at the turn of the century are for conservation, research and education. \"That underpins everything the society does to this day.\"