301 redirection can be used. It tells the search engines that any links & PR of the old URL now should be given to the new one.It is regarded as permanent move and safe move. Don't choose 302 redirection. And 301 redirection brings good experience to users.
We have something similar - we started off back in the day with a .net and then gradually went international with some CCTLDs, which are used for promotion in each country, mostly offline. However, each of these are just one page homepages which then link to our main .net site in the various languages, with no redirect. To avoid these pages being seen as doorway pages we link to all of them from the sitemap plus they're listed along with the contact details of each country. We haven't seen any issues, except for an unrelated panda problem, and often we're seeing the cctld close to the main site in the serps.