Every true Muslim should try his best to free himself from interest-based transactions, and it makes no difference whether one is living in a Muslim or a non-Muslim country. Above all, declaring sincere repentance and seeking Allah’s forgiveness from what has been done is very much needed.
Dr. Monzer Kahf, a prominent economist and counselor, states the following: Interest-based transactions are prohibited in the Shari`ah regardless of the location of the transactions or the religion of the other party.
If Muslims who live under non-Islamic law happen to be involved in interest-based transactions, they should make their best effort to get rid of such transactions in the shortest possible time. And until that time comes, they must honor the contractual obligations they put themselves in.