People in North Korea are voting in parliamentary elections that observers say could give a clue to the country's eventual succession.
The elections to the Supreme People's Assembly are always a formality, with each candidate elected unopposed.
But for the first time, one of leader Kim Jong-il's sons - Kim Jong-un - is rumoured to be on the ballot.
There has been much speculation over the health of Kim Jong-il, after reports that he had a stroke last year.
Mr Kim is not known to have named his successor and Western diplomats fear any leadership crisis could further raise tensions on the peninsula.
Grooming for power
The BBC's John Sudworth in the South Korean capital, Seoul, says that Kim Jong-un, the president's Swiss-educated third son, is thought to be his father's most likely successor.
Kim Jong-il is believed to have suffered ill health last year
It is a theory that would be given a boost if, as rumoured, the 26-year-old does make his first appearance on the ballot paper, our correspondent says.
Although Mr Kim is believed to have recovered from his apparent illness, and has maintained his tight control, it could take years to build support for any anointed son among the country's powerful military and party chiefs, our correspondent says.
Kim Jong-il's own grooming for power by his father, the first president, Kim Il-sung, took 20 years, he adds.
Sunday's election will also allow observers to chart the rising or falling fortunes of hardliners in the rubber-stamp parliament at a time when the country faces strong international pressure to give up its nuclear weapons programme, our correspondent concludes.
In the last elections in 2003, turnout was 99.9% and each candidate was elected unopposed with 100% of the vote.
Tensions between North and South Korea are high at present.
Six-nation talks on the aid-for-disarmament deal have stalled and North Korea's neighbours believe it could be preparing to test-fire a long-range missile under the guise of a satellite launch.
Earlier this week, North Korea raised objections to an annual US-South Korean military exercise due to start on Monday, warning that "security cannot be guaranteed for South Korean civil airplanes" during the drill.
As a result, two airlines in South Korea are to re-route flights to avoid North Korean airspace.
The top US envoy on North Korea, Stephen Bosworth, is visiting the region in an effort to breathe life into the stalled nuclear disarmament talks.
Speaking on Saturday in South Korea, the last leg of his tour, Mr Bosworth warned Pyongyang against launching a missile, saying it would be "ill-advised".
He also urged Pyongyang to drop its belligerent tone toward its southern neighbour, following its warning about the safety of commercial airlines.
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