Lost star Nestor Carbonell has revealed that episodes 9 and 15 will provide lots of answers for fans.

Speaking to E! Online, Carbonell - Richard Alpert on the series - said that viewers can expect a "big shock" from his character's episode.

"For those who had questions specifically about my character - why he doesn't age and his history - you're gonna get some answers [in episode 9].

"But you are gonna get broader answers about bigger questions like the island. It definitely reveals a lot. There are still more questions after that, but you're gonna get a big shock that week."

He added: "Episode 15 is a huge reveal. Episode 9 will give you big answers about the island but episode 15 even more so."

Lost continues Tuesdays at 9pm on ABC in the US