Thousands of frustrated marathon runners from around the world descended on New York's Central Park on Sunday to take part in improvised races after the famed event fell victim to superstorm Sandy.

Many put on the race numbers they would have worn in the marathon, a huge earner for the city, which was called off for the first time in its 42-year history.

Under a crystal blue sky, more than 3,000 runners started the Run Anyway NYC Marathon. Similar numbers took part in other races intended to ease the sporting anger at the cancellation.

Lance Svendsend put up a Facebook page proposing the race and soon built up the entry field as word spread.

Many of the 47,000 competitors were angered at the last-minute decision to call off the race on Friday when most runners were already in New York.

The organizers have still not announced whether or when they will refund entry fees for the race, which generates an estimated $340 million a year for the city.

Mayor Michael Bloomberg had wanted to carry on with the race, but gave in to protests over resources being devoted to the marathon while thousands still suffer from Sandy in New York.

Runners came from the four corners of the world to take part: Chileans, Croats, Canadians and Kazakhs. Many came from Europe.

Word spread about the Run Anyway marathon on social media sites. A lot of runners decided to donate cash to New York groups helping storm victims. Some just wanted to finish the miles and kilometers they had promised for sponsorship back home.

"It is very disappointing," commented Christophe Pujade from Carcassone in France. "This is a pilgrimage for us. We want to feel the sensation of the marathon and the atmosphere."

Elise Hinson, wearing race number 46789, came from Sydney having raised $4,000 for cancer research. She had the names of people who had died from cancer written on the back of her shirt.

"I just wanted to make sure that I finished the distance and the journey after coming all this way," she said.

Beatrice Rochette de Lempdes from Montreal in Canada said all the disappointed runners were in Central Park to show solidarity with each other.

"We are there together, we have a common passion, so it is good to be together today," she said.

Carlos Sanchez Rodriguez, a Spaniard, went to Central Park because he could think of nothing else to do on the big day. It would have been his sixth marathon.

"I'll go for a run and try and make it in my average time, but you have to be motivated," said Sanchez. "It is going to be difficult."

While many runners say they understand why the race had to be called off, there have been high-profile complaints about the way the cancellation was handled.

"I find it incredible that they let participants think this event was going to take place," wrote former French tennis star Amelie Mauresmo on Facebook.

One runner took Bloomberg to task. He ran in New York streets with a shirt bearing the slogan: "I love incompetent billionaires."

The marathon generates a lot of money for the local economy with 20,000 overseas runners in hotels and restaurants and some two million people lining the streets to watch the race.

Some runners paid up to $347 to enter and the organizers also get large amounts of money in television rights and other sponsors.

"We will have additional information in the days ahead, and we thank you for your dedication to the spirit of this race," said a statement on the Road Runners' website.