Lewis Hamilton says Mercedes should only employ team orders in "special circumstances" as Mercedes' policy of allowing the three-time champion and Valtteri Bottas to race continues to come under scrutiny.

Bottas was twice asked to let Hamilton past in Bahrain last time out, allowing the Briton to secure second place behind Sebastian Vettel.

The German leads the drivers' standings after two wins from three races, while Ferrari are top of the constructors' championship heading into this weekend's Russian Grand Prix.

Vettel appears a clear choice as Ferrari's number-one driver after a slow start to 2017 for Kimi Raikkonen, but Mercedes have not been moved on suggestions that they should pick one of Hamilton or Bottas to take the charge to him.

Asked if he agreed with team orders, Hamilton said: "I do not, and never have. 

"Team orders I think are always a very odd thing and a difficult thing to judge, and are something never to be liked. 

"It is in our rules and our approach is that the team need to win, so we do have to try and work as a team. But I think only in special circumstances."

Bottas in Thursday's press conference dismissed the notion that he was Mercedes' number-two driver, and Hamilton suggested that he would have been happy to let his colleague past if the tables were turned.

"I think I would have reacted exactly the same way as him," he said. 

"He was struggling, he's even admitted he was struggling with his rear tyres. When I went past, I said to the team if I don't pull away I'll let him back past, but I did.

"I could see Sebastian pulling away and I said we had to pick up the pace just at the time Valtteri was struggling with the car balance. It makes no sense for us both to fall behind and let them pull away. 

"In that scenario we worked as a team, and he while it was very tough for him, he was a great gentleman about it, and did the team proud."