lower developed countries
Typing it into Google gives around 1,200 results so it is in occasional use (less common is 'lower developed economies'). But the phrase seems ugly to me. After all, you wouldn't refer to 'low developed countries' (unless you meant the Netherlands, perhaps, which is both low and developed). Even with a hyphen, I don't like it.
But then, I've never really been keen on the phrase 'developing countries' either, which is what the OED gives. It seems arrogant to assume that countries such as the US and the UK aren't still developing. Unless, of course, they're moving backwards...
So what's the alternative – less-developed countries? At least that shares its acronym – LDCs – with 'lower developed countries'. Any other ideas?