FRANKFURT, Germany - Rocket Internet, the venture capital company behind online brands such as retailer Zalando, says investors' growing interest in internet businesses could help it more than triple its portfolio over the next five years.

Rocket, backed by Swedish investor AB Kinnevik, was founded in 2007 by the Samwer brothers Oliver, Marc and Alexander, who had an early success with mobile phone content provider Jamba whose offerings included the Crazy Frog ringtone.

Rocket's strategy is to take successful e-commerce models and then replicate them around the world. After starting the business in Europe, founder Oliver Samwer says the biggest opportunities are in emerging markets.

"We have roughly 75 companies today and in five years we want to have 200 to 250 companies around the world," Samwer told Reuters. Rocket's ventures in emerging markets include fashion retailers Dafiti in Latin America and Zalora in southeast Asia, as well as general merchandise retailer Jumia in Africa.

Samwer was speaking after Rocket said on Tuesday it had raised around $1 billion since the start of the year.

Of that, around $400 million has gone to Rocket from investors Kinnevik and Access Industries, while Rocket's ventures have raised the remainder from a range of investors, illustrating a desire for involvement in a sector which is still growing fast and is proving increasingly profitable.

GREAT OPPORTUNITY

"Raising money has been working very well for us," Samwer said by telephone.

"We have a lot of different investors - big institutional funds, big banks like JP Morgan, family offices and entrepreneurs as well as corporates like Kinnevik, so I think there's a very interesting base of people who see what we are doing as a great opportunity."

Speculation is mounting that Berlin-based Zalando, in which Rocket owns 36 percent and Kinnevik has 29 percent, could soon look to float on the stock market.

Samwer declined to comment on that possibility. Zalando's founders have said an IPO is not on the cards for now, as they focus on reaching profitability after having grown sales to 1.2 billion euros in four years.

Asked about Wimdu, a travel website that allows people to rent rooms in people's houses, Samwer said he was bullish despite competition from the likes of Airbnb.

Economies of scale do not improve with the number of countries you are in, Samwer said. "Therefore, in companies like Wimdu, it's much more important to be among the leading players in the German, French (or) Dutch market, focussing on Europe, instead of competing everywhere in the world."

Samwer said he believes setting up online businesses will keep him and his brothers busy for the next couple of decades.

"E-commerce is a trend that will not change for 20 years. There are trillions of dollars moving ... to online in the coming years," he said.