Although China is indicating it will implement new UN sanctions against North Korea more rigorously than previous embargoes, South Korea still does not expect Beijing to turn the screws fully on its communist ally.

The UN Security Council is expected to pass a raft of fresh sanctions against North Korea later on Friday, punishing the country for detonating an atomic bomb last month. But few diplomats believe these measures can really bite without support from China, which has traditionally been gentle on Pyongyang, fearing a regime collapse on its border.