Comic book superhero blockbuster The Avengers is set to become the third highest-grossing film in box office history, behind Avatar and Titanic.

Directed by cult favourite Joss Whedon, the Walt Disney Studios high-thrills action adventure made in collaboration with Marvel Comics earned $7-million over the weekend, for a total of $598-million since its release in early May.

And it was expected to cross the $600-million US box office threshold on Tuesday, Disney said in a statement.

Its global total, meanwhile, is now an estimated $1.4-billion.

The Avengers starring Samuel L. Jackson, Robert Downey Jr., Jeremy Renner, Scarlett Johansson and Mark Ruffalo was made for an estimated $220-million.

Released first abroad in April, it brings together a team of superheroes, which include Iron Man, the Incredible Hulk, Captain America and Thor, to help save the Earth from mythical prankster Loki and an alien army.

It opened in North America on 4 May with a staggering $207.4-million in ticket sales -- the biggest domestic weekend debut of all time -- and has been shattering domestic box office records ever since including the industry's all-time second weekend record with $103-million.

It was also the fastest film to reach $200-million, in three days.

The movie's success will help mitigate Disney's $200-million loss on the sci-fi fantasy film John Carter in March, which prompted the departure of Walt Disney Studios boss Rich Ross.

Only 12 films have grossed $1-billion at the global box office. Five of them are Disney films: The Avengers, two Pirates of the Caribbean chestnuts, Tim Burton's Alice in Wonderland and, in collaboration with Pixar, Toy Story 3.

The two greatest money-making movies were Canadian James Cameron's Avatar ($2.78-billion) and his Titanic ($2.19-billion).