Formula One's governing body has cleared Ferrari of any suspicion of cheating after rivals questioned the Formula One team's energy recovery system.
The International Automobile Federation (FIA) had been investigating after Mercedes and Red Bull raised concerns about what Ferrari were doing.
FIA race director Charlie Whiting said on Saturday that Ferrari's system was more complicated than that used by rivals but he now accepted everything was above board.
"We had some concerns in Baku (at the Azerbaijan Grand Prix in April) that were difficult to explain and we worked through it with them," said Whiting at the Monaco Grand Prix.
"(The rulebook) says that it is the duty of the competitor to satisfy the FIA that their car complies at all times and they were having difficulty satisfying us," he added.
"Here, we are now satisfied."
Whiting noted that a senior Ferrari engine designer had moved to Mercedes this season and said former Ferrari technical head James Allison, now in a similar role at Mercedes, had raised concerns.
"The matter was exacerbated by unsubstantiated speculation that went through the paddock like wildfire," said Whiting.
He said any information that might have travelled from Ferrari to Mercedes was likely to have been outdated.
The controversy burst out into the open on Thursday, when the official Formula One website reported that the FIA had asked Ferrari to "run an extra piece of hardware" so they could monitor the system.
The website suggested rivals had expressed concerns Ferrari might be boosting energy flow beyond the permitted limit.
