Ban Ki-moon urges North Korea to end missile tests
UN Secretary General Ban Ki-moon has called on North Korea to refrain from carrying out any further missile tests.
He was speaking as Pyongyang test-fired a fourth short-range missile over the weekend.
Such launches are routine but come as countries in the region are trying to break a stalemate in relations there, the BBC's Lucy Williamson says.
Mr Ban urged Pyongyang to lower the tensions in the region and "resume dialogue" over its nuclear programme.
Speaking in Russia after talks with President Vladimir Putin, Mr Ban called the missile tests "a provocative action".
Meanwhile, South Korea's defence ministry reported a missile launch from the North's east coast on Sunday.
The same ministry said on Saturday that Pyongyang had carried out three missile tests.
"I hope that North Korea will refrain from such actions," Mr Ban told Russia's RIA Novosti news agency.
"It is time for them to resume dialogue and lower the tensions. The United Nations is willing to help."
Mr Ban also called on Russia - a member of the stalled six-party talks on North Korea's nuclear programme - to help bring Pyongyang back to the negotiating table.
Tensions were raised this year between North Korea and its neighbours and the US.
Pyongyang threatened military strikes on targets in South Korea, Japan and the US following the imposition of new UN sanctions for its third nuclear test, and as annual US-South Korea military drills were being held.
As well as threatening to restart a mothballed nuclear reactor that produced plutonium for its weapons programme, Pyongyang also cut military and economic links with Seoul.
Intermediate-range missiles were deployed along the east coast in April but removed earlier this month in what was seen as a sign that tensions on the peninsula were lowering.