By Zaffar Abbas
BBC News, Islamabad
Two Swiss police officers are in Islamabad to help Pakistani officials investigate what is being described as a major human trafficking scandal.
Authorities are probing whether an organised gang is involved
Last week, the Swiss embassy decided to close its visa section and later to question some embassy diplomatic staff.
The move came after Pakistan's Federal Investigating Agency (FIA) arrested a Pakistani member of the visa section.
He and four travel agents are suspected of involvement in sending people abroad on fake or forged passports.
The issue which has rocked the Swiss embassy initially appeared to be a case of sexual harassment involving a Pakistani employee of the Swiss embassy.
Officers will question Swiss embassy staff
But as Pakistani newspapers continued to highlight the case, and federal investigators got involved, several new aspects came to light.
A Pakistani working in the embassy's visa section, Ashar Francis, was arrested and another employee declared an absconder.
Later on, four travel agents were picked up on suspicion of facilitating human trafficking.
Details of the case remain sketchy, but the Pakistani investigator dealing with the issue said the authorities were trying to find out if those arrested were part of some organised gang involved in sending Pakistani nationals to Europe on visas issued on fake or forged passports.
The FIA's additional director, Tariq Khosa, said it was difficult to say anything about the magnitude of the alleged trafficking operation.
But he said the most significant development had been the willingness of the Swiss authorities to question some of their nationals working at the embassy.
Mr Khosa said the two Swiss police officials sent from Bern met the FIA team to exchange details about the alleged trafficking operation.
Because of diplomatic restrictions the two sides had decided that only Swiss police officials would question diplomats from the embassy's visa section, he said.
The two sides would later exchange notes to ensure that there were no loopholes in the probe.
Mr Khosa said the investigation was continuing and would not rule out the possibility of more arrests or further revelations.