An audit of Swiss diplomatic representations has shown that 33 embassies and consulates face potential problems with corruption.
The information, published in the SonntagsZeitung newspaper, comes just days before a former employee of the Swiss embassy in Moscow goes on trial for selling visas.
Top of the list of representations deemed most at risk are Beijing, Moscow and Mumbai.
A foreign ministry spokesman confirmed that the list also included New Delhi, Istanbul, Kiev, Belgrade, Pristina and Bangkok. Fourteen of the representations are in Asia, ten in Africa and five in eastern Europe.
Corruption is considered most likely to crop up during the processing of Swiss visa applications, according to the ministry. Criminal groups involved in drug or human trafficking are said to be driving demand for fraudulent documents.
Spokesman Johann Aeschlimann said there was no link between the number of visa requests and the likelihood of corruption. But representations in China, Russia and India that top the list issue by far the most visas, turning down less than two per cent of applications in 2005.
Representations were judged on how many visa requests were made, how many were turned down, complaints from applicants and previous cases of irregularities.
Aeschlimann added that problems had cropped up in Rabat and Ankara, but had been dealt with swiftly. He said the main reason for the audit had been a visa corruption case that rocked the Swiss embassy in Islamabad and the consulate in Karachi.
In May Foreign Minister Micheline Calmy-Rey decided that all embassy staff in Pakistan, including the ambassador, should be replaced. In addition, three disciplinary investigations were opened.
Bern confirmed around 100 cases of visa fraud at the embassy.
Staff were implicated by a Pakistani man working at the embassy who had been arrested earlier in the year on charges of sexual harassment. He allegedly demanded sex from two women seeking visas.
Last year the Federal Prosecutor's Office investigated officials at six foreign missions – in Peru, Russia, Oman, Nigeria, Serbia and the Democratic Republic of Congo – for corruption. The charges concerned the alleged issuing of fraudulent visas mainly in return for bribes.
In November 2005, the former honorary Swiss consul in Oman was given a nine-month suspended prison sentence for falsifying visa application forms and charging over the odds for travel documents. Over a four-year period ending in 2003, the official pocketed SFr143,000.
On Thursday a former employee of the Moscow embassy goes on trial at the Federal Criminal Court in Bellinzona. The 49-year-old man is accused of selling visas to Indian nationals during a two-year period between 2001 and 2003, earning him nearly $20,000.
The employee has been charged with corruption, falsification of documents and breaking Swiss laws on foreign residency. His clients have not been located.
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The 141 Swiss missions abroad issue about 500,000 visas a year. 40,000 applications are rejected.
The number of visas issued should drop to about 400,000 once Europe's Schengen accord, doing away with border controls, comes into effect in Switzerland - at the earliest in 2008.
Switzerland is currently investigating cases of visa fraud in Peru, Russia, Nigeria, Serbia, Eritrea and Pakistan.