South Koreans who run factories in the suspended inter-Korean Kaesong industrial complex attend an emergency meeting in Seoul on Friday. (Ahn Young-joon/AP)

An inter-Korean industrial zone designed to act as a bridge between the estranged neighbors has become the front line of a battle between Seoul and Pyongyang amid rising tensions over recent missile and nuclear tests.

South Korea on Friday shut off water and electricity supplies to the complex near Kaesong, just over the northern side of the demilitarized zone that separates the Koreas. This came after North Korea on Thursday seized all the equipment and products housed in South Korean-owned factories in the complex, which Seoul had ordered shut the previous day.

“We expressed very grave regret over the North’s move,” Hong Yong-pyo, the South’s unification minister, said at a news briefing Friday. “North Korea should take full responsibility for what happens from now on.”

With the international community still mulling what sanctions it can impose on North Korea to punish the regime for last month’s nuclear test and this month’s long-range rocket launch, South Korea has acted quickly to inflict tangible pain.

In addition to ratcheting up ­anti-regime broadcasts across the DMZ and opening talks with the United States on a sophisticated missile defense system, South Korean President Park Geun-hye’s government on Wednesday ordered the shutdown of the Kaesong industrial complex.

More than 54,000 North Koreans were working in 124 South Korean-owned factories, making clothes, shoes and consumer goods, such as cooking utensils. Each earned about $160 a month — but their wages were paid to a state management company, not to them individually, leading to criticism that the project was propping up Kim Jong Un’s regime.

Park’s government on Wednesday explicitly accused North Korea of funneling the money, which totaled $120 million last year, into its nuclear and missile programs. Announcing the shutdown, the government said a “vigorous response” that “exacts a price for North Korea’s misguided actions” was required.

North Korea responded Thursday by expelling the 280 South Koreans who were at Kaesong, allowing them to take only personal belongings with them as they left.

It also said it would close the road that connected Kaesong to the South and shut down the last remaining cross-border communication hotlines.

The Kaesong industrial complex was established in 2004, when Seoul was pursuing a “sunshine policy” of engagement with Pyongyang, hoping to narrow the information and economic gap with the North. It was controversial from the start, with critics saying it was a way for the North’s regime to earn much-needed foreign currency.

Responding to the decision, the North’s Committee for the Peaceful Reunification of Korea called Park “a traitor for all ages” and said her decision constituted “an end to the last lifeline of the north-south relations . . . and a dangerous declaration of a war driving the situation in the Korean Peninsula to the brink of a war.”

“The south Korean puppet group will experience what disastrous and painful consequences will be entailed by its action,” the committee said in a statement carried by the official Korean Central News Agency.

With the seizure of the complex, the South’s Defense Ministry warned that North Korea could even turn the industrial park, just six miles north of the DMZ, into a military base.

“The military is keeping itself ready for every possibility,” Moon Sang-gyun, a spokesman for the Defense Ministry, told reporters Friday, according to the Yonhap News Agency. “If North Korea redeploys its troops, it may not be easy for the country to decide what to do with the Kaesong Industrial Complex, but we leave the possibility open,” he said.

The industrial park was shut down once before, in 2013 when North Korea withdrew its workers for five months in retribution for annual military drills between South Korea and the United States.

But no matter the provocation, South Korean governments have tried to set the Kaesong complex aside from political and military conflicts.

Even when North Korea sank a South Korean naval corvette in 2010, killing 46 sailors and prompting sanctions from the South, the zone remained operational.

The small and medium-size companies that were evicted from the complex voiced anger at the move, saying that the economic project was supposed to be run separately from political considerations.

Park’s government on Friday outlined measures to help the companies pay their debts and said that they could postpone the payment of taxes and utility bills.