North Korea is still committed to six-party talks on its nuclear programme, according to a British envoy.
South Korean media has been speculating about last week's blast
But UK Foreign Office minister Bill Rammell said he did not know when negotiations would begin again.
"Certainly one of the factors they are considering ... is the timing of the American presidential election" in November, he said.
Mr Rammell was talking in Beijing, after a four-day visit to the secretive Communist state.
China wants the talks to resume before the end of this month.
"At the end of those discussions, what was clear to me was
that the North Koreans were saying they were still committed to
the six-party talks process but weren't prepared to commit to a
date," he said, after holding talks in Pyongyang.
"I simply said to them, 'You have got to come back to the
While in North Korea Mr Rammell obtained a pledge that UK officials could visit the site of a huge explosion last week that raised fears of a possible nuclear test
UK ambassador David Slinn will lead a visit to the site, and "all the heads of missions in Pyongyang will be allowed to go on that trip," said Mr Rammell.
Pyongyang says the explosion was in fact the demolition of a mountain as part of a huge hydro-electric project.
The United States and South Korea had already played down suggestions that the explosion, near Yongjo-ri in Yanggang Province, was caused by a nuclear device.
"There was no indication that was a nuclear event of any kind. Exactly what it was, we're not sure," US Secretary of State Colin Powell told ABC television on Sunday.
The blast is said to have happened on Thursday as the Stalinist state celebrated its National Day.
It created what officials in Seoul said was a huge, and peculiarly-shaped, cloud.
North Korea is under international pressure to end all nuclear programmes and disarm.
But so far it has offered only limited concessions during "six-party" international talks involving both Koreas, the US, China, Russia and Japan.