A satellite sent into space by North Korea is in orbit but it is not yet clear whether it is working, South Korea's defence ministry has said.

The North has said the Kwangmyongsong-4 is a communications satellite and that Sunday's launch was a complete success.

But the move was internationally condemned as North Korea is banned under UN sanctions from using any ballistic missile technology.

The UN has vowed to impose further sanctions as punishment.

The US said on Monday that this could include "a range of economic sanctions that would further isolate North Korea" and send a clear signal "that the resolve of the international community here is firm".

The US has also said it will help South Korea deploy an advanced missile defence system as soon as possible, officials from the Pentagon have said.

The South's defence ministry said the launch indicated the North now has long-range missiles with a 12,000km (7,500-mile) range, the Yonhap news agency reports.

But it remains unclear whether it has developed the technology to make a missile re-enter the atmosphere, critical if it is to use the missile as as weapon.

The North insists its space programme is purely scientific in nature but the US, South Korea and even Pyongyang's ally China say the rocket launches are aimed at developing inter-continental ballistic missiles.

Last month North Korea also carried out its fourth test of a nuclear bomb.

North Korea's rocket launches

February 2016: Launch of rocket reportedly carrying satellite

May 2015: North Korea announces it has successfully tested a submarine-launched missile for the first time, but scepticism is then poured on the claim

Dec 2012: North Korea launches three-stage rocket, says it successfully put a satellite into orbit; US defence officials confirm object in orbit

Apr 2012: Three-stage rocket explodes just after take-off, falls into sea

Apr 2009: Three-stage rocket launched; North Korea says it was a success, US says it failed and fell into the sea

Jul 2006: North Korea test-fires a long-range Taepodong-2 missile; US said it failed shortly after take-off