By Jon Herskovitz

SEOUL, March 29 (Reuters) - South Korea's military said on Saturday there were no signs North Korea would again test-fire missiles, a day after it launched a barrage of short-range rockets and threatened to attack the South Korean Navy.

In the past few days, North Korea has also expelled South Korean officials from a joint factory park just north of the border and threatened to slow down a nuclear deal in what analysts said was a show of anger at the new conservative South Korean government and its ally the United States.

"We are not seeing any further signs of particular movements that would indicate additional missile launches. We suspect the situation is over after yesterday's launch" a public affairs official at the Defence Ministry said.

North Korea, which has a habit of test-launching missiles as a way to ratchet up political tensions, shot off ship-to-ship missiles into the Yellow Sea on Friday.

It also said if South Korean ships continued to patrol in disputed Yellow Sea waters, there could be a battle.

In Washington, White House spokesman Gordon Johndroe said missile testing was "not constructive" and should end.

South Korean President Lee Myung-bak's government, in office for a month, has told its touchy and destitute neighbour that if it wants to keep receiving aid, it should clean up its human rights, abide by an international nuclear deal and start returning the more than 1,000 South Koreans it kidnapped or has held since the 1950-53 Korean War.

Lee's left-of-centre predecessors in the presidential Blue House for the past 10 years have sent billions of dollars in aid to the North while asking for little in return, seeing it as the price to pay for stability on the heavily armed peninsula.

North Korea's official media has criticised conservatives in South Korea for trying to upset once-warming ties, while Seoul has said it is ready to send massive aid to the North, but it expects its prickly neighbour to offer something in return.

The North Korean moves come as conservatives are trying to take over control of the South's parliament from left-of-centre forces in an April 9 election. If conservatives win a majority, Lee's hand would be strengthened for several years.

"North Korea is creating an atmosphere of tension in response to the government pursuing a hard-line policy toward Pyongyang," said Koh Yu-hwan, an expert on the North at South Korea's Dongguk University.

At about the same time as the Friday launch, North Korea's official media fired a rhetorical volley at the United States, blaming it for pushing into deadlock six-country talks aimed at ending the North's nuclear arms plans.

Pyongyang began disabling its Soviet-era nuclear plant that produces plutonium for weapons late last year as part of a deal with regional powers in return for aid and an end to international isolation.

The process has reached a stage where it would likely take it at least a year to get its Yongbyon nuclear plant running again, South Korean officials said. (Additional reporting by Lee Jin-joo; Editing by David Fogarty)

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