HANOVER, Germany — Russian President Vladimir Putin expressed concern on Monday about the escalating tensions on the Korean peninsula and said conflict there could cause greater devastation than the Chernobyl nuclear disaster in 1986. Meanwhile, activity at N. Korea nuclear test site hints at another test. “I would make no secret about it, we are worried about the escalation on the Korean peninsula, because we are neighbors,” Putin told a joint news conference with German Chancellor Angela Merkel during a visit to a trade fair in Germany. “And if, God forbid, something happens, Chernobyl which we all know a lot about, may seem like a child's fairy tale. Is there such a threat or not? I think there is... I would urge everyone to calm down... and start to resolve the problems that have piled up for many years there at the negotiating table.” Putin also praised a US decision at the weekend to postpone a planned missile test as part of efforts to reduce tensions on the Korean peninsula. “I think we should all thank the US leadership for this step. I hope it will be noticed by our North Korean partners, that certain conclusions will be drawn, everyone will calm down and start joint work to ease the situation.” North Korea may be preparing for a fourth nuclear test, with stepped up activity detected at its main test site, a senior South Korean government official said according to a report Monday. “We are closely monitoring the ongoing situation, which is very similar to the situation seen ahead of the third nuclear test,” the unnamed official told the daily JoongAng Ilbo. South Korean intelligence authorities have detected unusually busy personnel and vehicle movements at the Punggye-ri nuclear test site in the country's northeast since last week, the government official reportedly said. “We are trying to figure out whether it is a genuine preparation for a nuclear test or just a ploy to heap more pressure on us and the US,” the official added. The heightened activity has been detected near a tunnel at the south side of the atomic test site, the official added. The newspaper cited a senior military official as saying that the North was capable of staging another nuclear test “within several days once a political decision is made.” — Agencies