Shocked diners were ordered to leave two Inverness restaurants after immigration and police officers swooped on the premises.
Simultaneous raids are also thought to have taken place at restaurants at Forres and Nairn on Thursday night and the early hours of yesterday.
Immigration officials from the UK Border Agency and Northern Constabulary officers are believed to have targeted two Indian restaurants in Inverness that have previously come under scrutiny for employing illegal immigrants.
Jeera, in Queensgate, and Shapla, in Castle Road, were both raided on Thursday, with staff questioned by officers, it is thought.
It is also understood that two staff members fled one of the restaurants, before being stopped by officers close to Inverness Castle.
Customers who were eating at the restaurants or had ordered food were told to leave.
It was unclear last night if documents were seized or arrests made because the operation is “ongoing”.
A spokesman for the UK Border Agency said: “Officers, with support from police forces in Scotland, are carrying out an operation into immigration-related crime.”
Shabaro Ali, the owner of Jeera and Shapla, could not be contacted at either of his Inverness restaurants yesterday, or at his home at Pilmuir Road, Forres.
Both restaurants were open for business last night.
The restaurants were fined last year after they were found to be employing illegal immigrants. Shapla was fined £1,440 after admitting five breaches of the Asylum and Immigration Act 1996 and Jeera Inverness was fined £720 for three breaches.
Jeera and Shapla were among a number of restaurants raided by officers from the Border and Immigration Agency on two separate occasions in 2007.
Mr Ali is accused of 14 hygiene offence in relation to Shapla, including failing to ensure premises were kept clean and maintained and failing to ensure the kitchen was protected against pests.
The case called at Inverness Sheriff Court this week and was continued without plea until next month.