Alex Salmond has accused the Coalition Government of threatening Scotland's relationship with China after two teachers from the country were told they had just days to return home.

The First Minister has ­intervened after the Home Office refused to renew visas for two members of staff on a Scottish Government-funded scheme to teach Scots pupils Mandarin.

In a letter to the Home ­Secretary Theresa May, Mr Salmond, who is currently on a trade mission to the country, said he was shocked and dismayed by the decision.

The two teachers were working with the Confucius Institute for Scotland's Schools (CISS), which is sponsored by the Scottish Government.

Last week the CISS was told that the two, who had returned to Scotland to resume teaching for a second year as planned, had had their visa ­renewals refused.

The teachers, who have not been named, work in Scottish schools helping pupils to learn Mandarin and gain an awareness of Chinese culture.

The scheme, which began in 2010, is jointly funded by the Chinese, who continue to pay the teachers' salaries while they work in Scotland, and the CISS, which pays for their accommodation and certain other costs.

It is thought to be the first time the organisation has faced such problems. Last year, two other teachers successfully extended their stay in Scotland to two years.

Fhiona Fisher, acting director of SCILT, Scotland's National Centre for Languages at the University of Strathclyde, which hosts the CISS, said: "The Confucius Institute for Scotland's Schools values greatly the contribution of the exchange teachers to language learning in Scotland through this joint programme with China. We hope this situation will be resolved swiftly."

In his letter to Mrs May, Mr Salmond said he was "shocked and dismayed" that the visas had been refused.

He appealed to the Home ­Secretary for an assurance that further action would be suspended until the matter was properly investigated. He described the teachers as an "immensely valuable asset to young people in Scotland, bringing benefits to our society and our economy".

He also said experience had shown that having them return to Scotland for a second year of teaching had proved highly ­beneficial to young learners.

He said Scotland was an "open an outward-looking nation, welcoming to those who enrich and enhance our society, adding: "The ­Scottish Government does not welcome actions which threaten this."

He wrote: "To seek to remove these teachers will undermine this successful project and damage Scotland's relationship with China. This is effectively sabotage of a Scottish Government initiative and I can think of no sensible reason why you would not reverse these decision."

A Home Office spokeswoman said: "We have received the letter from the Scottish Government and we have been in contact with them over these cases.

"We are taking this matter ­seriously and will be looking into the decisions."

Meanwhile, UK Government plans to force visitors from "high risk" countries to pay a £3000 security bond to enter the UK have been scrapped.

Ms May's scheme was due to be piloted from this month as a way of deterring temporary visitors from staying on in the UK after their visas expire.

It had been suggested that ­visitors from India, Pakistan, Sri Lanka, Bangladesh, Ghana and Nigeria would be required to pay the deposit for a six-month visa, but it is understood the scheme has now been scrapped.

Deputy Prime Minister Nick Clegg said he was capable of stopping the plans.

He added: "I am absolutely not interested in a bond which becomes an indiscriminate way of clobbering people who want to come to this country, and in many respects bring great prosperity and benefits to this country."