Christoper Nolan's Inception has retained the US box office top spot in its second week on release, with new action film Salt debuting in second.

Inception, starring Leonardo DiCaprio and Ellen Page, took an estimated $43.5 million in its second weekend on release to retain the number one spot as Angelina Jolie thriller Salt debuted in second with $36.5 million.

Warner Bros attributed Inception's continued box office success to positive word-of-mouth among older filmgoers after a strong debut among the under-35s.

"To have a hold of this stature is definitely a rarity among big summer blockbuster movies," president of domestic distribution Dan Fellman told Variety.

"This is a smart, original film that has taken on a life of its own."

The only other new entry in the US top ten was children's film Ramona and Beezus, debuting in sixth with an opening weekend worth $8 million.

The top ten films at the US box office are: (last week's position)

1 Inception (1)
2 Salt (-)
3 Despicable Me (2)
4 The Sorcerer's Apprentice (3)
5 Toy Story 3 (5)
6 Ramona and Beezus ()
7 Grown Ups (6)
8 The Twilight Saga: Eclipse (4)
9 The Last Airbender (7)
10 Predators (8)