Bernie Ecclestone has ordered a 'hard but fair' conclusion to the 2008 championship, as rivalries threaten to spill onto the circuit with two races to go.

Title leader Lewis Hamilton at Fuji accused his opponent Felipe Massa of deliberately crashing into him.

The first official press conference at Shanghai, meanwhile, was a noticeably tense affair, particularly after Hamilton's nemesis Fernando Alonso promised to help Massa to defeat the Briton.

"We want fair play at all times," Ecclestone, F1's chief executive, told the Gulf News newspaper. "Hard and close racing, yes, but fair play, too without drivers being put in danger.

"The wider world is watching and waiting the outcome of what has turned into a great championship. We don't want it spoiled and we will crack down on any dirty tricks," the 77-year-old added.

In China, however, Spaniard Alonso clarified that he was never planning to hinder Hamilton by using dirty tricks.

"If Felipe wins the race and I can be second or third I will be happy to help Felipe to take as many points as possible and this is the only approach," said the Renault driver.