A Jordanian farmer and three members of the security forces were killed Thursday when two old mines exploded, a security source said.
The first mine went off in a field killing the farmer and the second exploded when security forces came to investigate, killing three of them and wounding seven others, the source said.
Jordan had more than 300,000 landmines laid across its territory, most of them in the Jordan Valley during successive Arab-Israeli wars, but also near the borders with Iraq and Syria.
The blasts occurred in the Salt region, northwest of Amman, which lies near the Jordan Valley and the border with Israel.
Some mines date from the Six-Day War of 1967 in which Israel seized the West Bank from Jordan and from 1968 when Salt was a key battlefront where artillery units were deployed to thwart an Israeli attack on the Jordan Valley village of Al-Karameh.
The security source on Thursday did not confirm that the deadly mines dated to wars with Israel but said an investigation was underway.
Over the years Jordan has sought to clear its territory of mines, allowing farmers to reclaim land.
Last year, Israeli and international experts began clearing thousands of wartime landmines and explosive devices from the occupied West Bank, in an area where some people believe Jesus was baptised.
Israeli military officials said those mines dated from the Six-Day war.