Pakistani authorities on Tuesday released 11 Iranian Revolutionary Guards detained a day earlier for trespassing into Pakistani territory, officials said.
The guards were arrested in the Mashkhel area on the border with Iran eight days after a suicide bomber killed 42 people, including six Revolutionary Guard commanders, in Iran's southeastern Sistan-Baluchestan province.
A Sunni Muslim group, Jundollah (God's soldiers), claimed responsibility for that blast and Iran said the group operated from Pakistan. On Tuesday last week, a senior Revolutionary Guards commander said his force should be given permission to confront terrorists inside Pakistan, state media reported.
Officials said the 11 Iranians Guards arrested on Monday had accidentally strayed in Pakistan territory. Iranian state television they were arrested while pursuing suspected fuel smugglers.
"The guards were handed over to the Iranian authorities because it's found that they crossed into Pakistan mistakenly," said a spokesman for Pakistan's Frontier Corps paramilitary force.
Relations between Iran and Pakistan have generally been good, but tension has risen after Iran said last week's suicide bombing would affect relations.
Iran says the Jundollah group has bases in Pakistan and it has urged Pakistan to hand over its leader, Abdolmalik Rigi.
Pakistan has assured Iran that it would cooperate in tracking down and punishing those behind the attack but has denied that Rigi was in Pakistan.
Iran also accuses the United States and Britain of backing Jundollah.