ZURICH (Reuters) - Almost 129,000 Volkswagen (>> Volkswagen AG) group vehicles registered in Switzerland are affected by the rigged emissions testing scandal that has halted Swiss sales of new models equipped with the diesel motors in question, VW's Swiss distributor AMAG said.

VW, which has admitted to cheating on diesel emissions tests, is under huge pressure to get to grips with the biggest business scandal in its 78-year history.

In a statement on Monday, AMAG said 128,802 cars in Switzerland were affected by the scandal, equating to 2.2 percent of the 5.8 million road motor vehicles in Switzerland at the end of 2014.

AMAG said the affected models were Volkswagen, Audi, SEAT, SKODA and VW commercial vehicles.

Switzerland's federal roads agency ASTRA also said it thought around 130,000 vehicles on Swiss roads may be affected, revising lower an initial estimate on Friday of around 180,000.

Just how many diesel vehicles built between 2009 and 2014 actually had manipulated software was still under investigation, it said in a statement, reiterating it aimed to block sales of new cars or imported used cars from this group.

Cars already registered in Switzerland could still operate.

As part of VW's action plan to solve the crisis, AMAG said a plan to retrofit the affected cars would be presented to Swiss transport authorities in October.

Only a few hundred new cars in AMAG's inventory were affected by the sales halt, it added.

(Reporting by Joshua Franklin; Editing by Mark Potter and David Evans)