Seoul, April 12 : North Korea remained unresponsive to daily routine calls with South Korea through an inter-Korean liaison communication channel for a sixth straight day on Wednesday, Seoul's Unification Ministry said. The North was unresponsive to the 9 a.m. routine opening calls, and has not answered the calls from the South since April 7, according to the Ministry. Seoul's opening call via the militaries' East and West seas communication lines also went unanswered, reports Yonhap News Agency. The two Koreas typically hold two phone calls daily, at 9 a.m. and 5 p.m., as part of communication between liaisons. In July 2021, the North restored the inter-Korean hotline, about a year after it severed the contact channel in protest of Seoul activists' leaflet campaigns critical of Pyongyang. The liaison line was again cut off in August that year for about two months in apparent protest against Seoul-Washington's military exercises. The latest suspension of the hotlines comes amid heightened tensions on the Korean Peninsula following the North's recent weapons tests in protest of joint military drills between South Korea and the US. On Tuesday, South Korean Unification Minister Kwon Young-se issued a rare statement expressing "strong regret" over the North's "unilateral and irresponsible" move. /IANS