A couple of points:
- You are not "releasing equity" by remortgaging: you are simply borrowing. Despite what banks would have you believe by using terminology like this, the only way to release equity in something is to sell it.
- As has been pointed out in a recent thread, rent is no more dead money than interest payments.
The question you should be asking is whether it makes sense to borrow cash secured on a house here in invest in a property abroad, keeping in mind there's no absolute guarentee rental income (net of all expenses) would actually cover the cost of repayments.