Scotland's best paid charity boss has hit back at criticism of his salary, arguing it is justified by the results achieved under his leadership.

Stuart Earley, the chief executive of the animal charity SSPCA, has been described as a charity 'fat cat' by the media and other charity campaigners after it was revealed that bonuses took his income last year to £216,000.

His basic salary is understood to be in the region of £185,000, making him among the UK's best paid charity leaders and far outstripping that of the heads of most of Scotland's larger charities, as well as the prime minister and first minister.

The head of a rival animal charity John Robbins of Animal Concern was quoted as saying that he could hire nine or ten campaigners for the same money and warning that the public might stop donating if he donations from pensioners appeared to be funding luxury lifestyles for charity executives.

However Mr Earley described coverage of his pay, which is set independently by a charity remuneration board, as 'frustrating', given that the charity now helps twice as many animals annually as when he took over. "It is a team effort, but I can't think of many charities achieving that same level of increase," he said.

By comparison, he said, the RSPCA in England and Wales has seven times the income of the Scottish charity and five times the staff, but only helps twice as many animals.

"The true test is how well we are achieving the charity's objectives and the proportion of income we spent on those activities," he added, pointing out that the Charity Choice website estimates the SSPCA spends 87 pence in every pound donated on its frontline work.

The charity says the actual figure is lower, at around 83 pence in the pound, but it still operates with lower overheads than the majority of charities.

Mr Earley's bonus last year was in recognition of such achievements, particularly some challenging targets which the charity set for itself in 2009, he said.

These included increasing the number of schoolchildren reached with education work from 27,0000 to 150,000 by 2014. He says the actual figure reached is now 317,000 a year. Meanwhile membership was to be increased from 31,000 members to 50,000 members by 2014. It actually topped 52,000, he says. "These were very tough and challenging targets to hit. That is why the bonus payment was made. It is down to performance."

The SSPCA's trustees, who have rallied round Mr Earley, also point out that under his leadership a black hole in the charity's pension funds has also been eliminated.

Mr Early said he did not know whether his salary was out of kilter with other Scottish charity heads, adding: "I haven't looked - I don't know what everyone else is being paid. Some people think all charities should be run by people who don't earn anything.

"I can understand the frustration if someone is being paid a high salary and they are not performing. But you have to look at what the performance is."

Linking his pay rises to the closure of some services was unjustified, he said. While the SSPCA did close a wildlife rescue centre in Shetland last year, this has resulted in a overall improvements, Mr Earley claims. "It was essentially like a brick bungalow outdated, and too small. Most of the time it was unmanned, and now we are able to respond to more than twice as many call-outs.

"But overall we are not closing services down. We have opened services, spending £15m on a capital programme which has included developments in Edinburgh, Aberdeen, Inverness and Glasgow."