Rockstart, a startup accelerator program based in Amsterdam, has announced that it’s going to offer additional support to its companies after Demo Day, when most schemes of its kind finish.

The three-month summer program will include 25 days of co-working in the U.S. During this time, startups will relocate to Silicon Valley and Las Vegas, where they will be introduced to investors, experts, and media relevant to their field of business.

Rockstart says that research amongst startups found that they felt they would benefit from continued support after the traditional end point of an accelerator scheme. Startups will be offered the opportunity to stay on beyond Demo Day to take advantage of the summer program if they choose – it’s not mandatory. Rockstart takes an 8% equity stake in each startup that it accepts into its program and there’s no additional cost to take part in the extension.

Rockstart’s 2012 program will take on ten startups with high potential, offering them access to 99 mentors throughout its 100 day program, before letting them pitch to investors. It starts on 1 March and applications are open from today until 6 January 2012.