Seoul, Jun 22 (IANS): North Korea is preparing to hold a large-scale military parade to mark the 75th anniversary of the founding of the ruling Workers' Party, South Korea's Defence Ministry said on Monday, amid speculation that Pyongyang could showcase new strategic weapons.

In a report to Parliament's defense committee, the Ministry said new buildings were spotted under construction at the Mirim airfield in Pyongyang, a possible sign the North could showcase an intercontinental ballistic missile (ICBM) or a submarine-launched ballistic missile (SLBM) on October 10, reports Yonhap News Agency.

"The North Korean military is continuing activities to prepare for an event to celebrate the 75th anniversary of the establishment of its party," the Ministry said in the report, adding that repair work for Kim Il-sung Square was also underway.

The North has used military parades on important national days to flex its military muscle by displaying newly developed weapons, including missiles.

It usually holds bigger events to celebrate anniversaries every fifth or 10th year.

The Ministry said no unusual movements have been detected in relation to the North's nuclear program, but missile development activities have continued.

The assessment came amid a surge in cross-border tensions after North Korea blew up an inter-Korean liaison office in its border town of Kaesong last week in anger over anti-Pyongyang leaflets sent across the border by activists here, said the Yonhap News Agency.

The North has since threatened to send troops to disarmed border regions and abolish an inter-Korean tension-reduction deal signed in 2018.

South Korea and the US have boosted their joint monitoring and intel-sharing in light of the North's threats and will carry out their combined exercises this year at a level similar to last year's, the Ministry added.