SEOUL -- South Korea on Tuesday rejected an offer by North Korea to change the venue of proposed talks, casting doubts over the inter-Korean peace process which was put back on track after a six-month hiatus.

Unification Minister Hong Soon-Young stressed that South Korea's tightened security cannot be the reason for the North to change the venue of inter-Korean talks.

"South and North Korea must respect agreements and practices under which talks have been held alternately (in Seoul and Pyongyang)," Hong said in a telephone message to the North.

In the wake of last month's terrorist attacks in the United States, the North abruptly called off reunions of families torn apart since the 1950-1953 Korean war because of what it deemed the tense atmosphere created in the South, AFP reported.

North Korea, citing security concerns, has insisted all inter-Korean talks must be held in its territory.

"It's rational to hold the talks at Mount Kumgang (in the North) where security is guaranteed," Pyongyang said earlier Tuesday.

But Hong stressed the two Koreas should hold talks this week in the South's Mount Sorak on ways to promote cross-border tours, and economic talks next week in Seoul as previously agreed.

"There will be no security problems on our side," he said, urging the North to reschedule family reunions.

The two Koreas agreed to put their faltering peace process back on track when they resumed talks last month. But the north is still reluctant to build a railway and land routes across the demilitarized zone.

In putting off the fourth round of family reunions, the North warned that the South's tightened security created "an unpredictable atmosphere of tension".

North Korea, still on a us list of states backing terrorism, has reportedly put armed forces on heightened alert after the terror attacks in the United States.

The North's move came in response to security steps taken by the South Korean military.

South Korean troops have been put on alert. The United States has deployed new military planes here to fill a security vacuum caused by the relocation of a U.S. aircraft carrier.

Some 37,000 U.S.troops are stationed in the South to guard against hostilities with the North.