Volkswagen AG has called off the next round of talks over a planned integration with sports car maker Porsche SE, saying the atmosphere is not right for constructive discussions, officials said Sunday. The Wolfsburg-based car maker had pulled out the next round of talks at the working-group level that were scheduled for Monday, VW spokeswoman Christine Ritz told The Associated Press. VW chairman Ferdinand Piech and members of the Porsche family - controlling shareholders of Porsche Automobil Holding SE - will come together as planned at a meeting of Porsche's supervisory board Monday, she said. Porsche declined to comment. Earlier this month, Piech and the Porsche families agreed on a plan to integrate the Porsche car-manufacturing group with Volkswagen, under which the independence of the 10 brands of both companies would be ensured. But Piech threw the plan into question Tuesday, by saying Porsche must reduce its debt before an integration could be possible, referring to the â‚¬9 billion in net debt Porsche took on as it brought its stake in Volkswagen up to 51 percent last year.