A North Korean defector group said Friday that it has temporarily suspended a plan to float plastic bottles containing rice into North Korea amid heightened cross-border tensions.

Keunsaem had pushed to send plastic bottles containing rice from the western border island of Gangwha on Sunday, but the plan was put on hold temporarily in the face of the North's repeated retaliatory threats over such activity, according to a notice posted on its website.

North Korea has ratcheted up tensions over the sending of anti-Pyongyang leaflets and other materials by defectors.

The North blew up a joint liaison office in its border town of Kaesong earlier this week and threatened to take more retaliatory steps. Earlier the North's state media warned that the next step could go "far beyond imagination."

South Korea has called for a halt to leafleting, saying that it could further aggravate inter-Korean tensions and undermine the safety of residents near the border.

Last week, the unification ministry filed a criminal complaint against two activist groups -- Fighters for Free North Korea and Keunsaem -- over the leafleting issue.

Activist groups have insisted that sending leaflets and rice into the North is part of its right to freedom of expression.

Fighters for Free North Korea said that it will go ahead with a plan to send leaflets into the North next week. (Yonhap)