Fey got dialect coach for Muppets role

Tina Fey says she took the advice of a dialect coach to perfect a Russian accent for Muppets Most Wanted, imagining she had "a piece of poop" on her lip.

Tina Fey says she worked with a dialect coach to perfect a Russian accent for Muppets Most Wanted. (AAP)

Tina Fey worked with a dialect coach to perfect her Russian accent for her new film Muppets Most Wanted.

The former 30 Rock star, who plays a Russian government agent in the puppet parody, did not take her role lightly. When she started to struggle with her accent, she agreed to work with an expert.

"They (producers) brought this wonderful woman named Jill, who is like a real dialect coach, this British woman who works with like Keira Knightley."

The coach, Fey says, imparted some important advice: "When you go to do it, it's actually really hard, the Russian, and she told me the tip to remember: 'You're supposed to (act like) you have a piece of poop on your lip, that you want to get this piece of poop off your lip, that you hate everything.'"

Fey took the advice to heart: "So I was thinking, 'I have this piece of poop on my lip', and I was trying super hard and I think I did pretty good."

Muppets Most Wanted is due to open in Australia in April.