BARCELONA, Spain - Lotus' Formula 1 team owner Gerard Lopez has criticised engine-supplier Renault, after the automaker revealed some of its customers are behind in payments.Renault F1 managing director Jean-Michel Jalinier's comments at the 2014 Spanish GP triggered rumours about the future of Caterham. Suspicion also fell on Lotus, who in 2013 were famously late to pay Kimi Raikkonen. Lotus driver Romain Grosjean was not paid by struggling Lotus in 2013, although he said in April 2014 he kept the problem quiet.'IT WAS MY BUSINESS'Grosjean: "I never opened my mouth in front of the media because it was my own business, my personal thing."Lopez has now hit back at Renault for suggesting some teams have failed to pay for their new turbo V6 power units in the 2014 season.Lopez said: "I said to them if they are going to say things, then name the team that is an issue. Don't just say 'teams' and then expect people to make their own judgements."If there is (a team that has not paid), it must be another team, but I'm not even sure there is, to be honest with you."Stay with Wheels24 for the 2014 F1 season – fresh reports every day.