Hannibal Gaddafi's arrest sparked a major diplomatic spat
Libya has stopped issuing visas to citizens from many European nations, in apparent retaliation for alleged Swiss measures against the Gaddafi family.
Diplomats say Libya has barred people from the Schengen zone - which includes 25 European countries.
Reports say the measure is already in force at Tripoli's main airport.
It follows an extended row that began with the arrest of Libyan leader Muammar Gaddafi's son and daughter-in-law in Switzerland in July 2008.
The charges, of mistreating two domestic employees, were later dropped.
Libya then halted oil exports to Switzerland, withdrew billions of dollars of assets from Swiss banks and put two Swiss businessmen working in Libya on trial for visa violations and other offences.
At the weekend a Libyan newspaper reported that Switzerland had drawn up a visa blacklist that included Colonel Muammar Gaddafi and his family.
The paper said the North African country would take "severe measures" in response.
The Schengen zone consists of 25 countries which have abolished mutual border controls. They include 22 of the 27 European Union member states, plus three others, one of which is Switzerland.
A senior European diplomat has confirmed to the BBC that European embassies have been officially notified by Libyan authorities of the ban on entry-visas for citizens from Schengen zone countries.
A German foreign ministry spokesman described the move as "regrettable".
EU members UK, the Republic of Ireland, Cyprus, Romania and Bulgaria are not part of the Schengen zone.
The measure seems unlikely to remain in the long term, says the BBC's Rana Jawad in Libya.
Italy in particular has been enjoying a new-found friendship with Libya since it agreed to compensate for its colonial past, she says.
Italy and Austria are some of the Schengen zone countries investing in Libya's oil sector and there are also major investments in construction and other industries.