TEHRAN — A large explosion at Iran’s main energy pipeline hub Friday was caused by sabotage, an influential member of Parliament said Sunday.

The blast, which sent balls of fire into the air outside the Shiite religious center of Qom, targeted three major gas pipelines. The explosion comes amid an increase in mysterious blasts, assassinations and other incidents in the Islamic Republic, including a similar blast Feb. 11 that temporarily halted north-south gas transportation in the country. All pipelines are now back in operation, officials say.

Parviz Sorouri, a member of the National Security Commission, called for increased protection of Iran’s oil and gas pipelines. He also announced a meeting of key ministries to safeguard the Islamic Republic’s energy transportation systems.

“Terrorist groups have sabotaged gas transfer pipelines in Qom province in order to create insecurity in the energy transfer path of the country,” Sorouri told the semi-official Mehr news agency. He did not provide further details about who may have been responsible for Friday’s explosion.

Iranian officials have connected the past year’s incidents to actions by foreign-backed terrorist groups or to unexplained accidents. Iran’s leaders blamed the United States, Britain and Israel for two separate high-profile assassinations of scientists in Tehran last year. But a major explosion at a Revolutionary Guards base near the city of Khorramabad in October that killed an unknown number of servicemen was said to be caused by a fire at a munitions depot.

In recent weeks, six Iranian security officials in the ethnic province of Kurdistan have been assassinated by unknown assailants. That region was also the scene of a mass bombing in September that killed 12 members of the Revolutionary Guards, including commanders. Iran has blamed a separatist group, which it says is backed by the United States, for the killings. But the Party of Free Life Kurdistan, or Pejak, has strongly denied playing any role in either the assassinations or the bombing.

The incidents come amid increasing tensions between Iran and the Persian Gulf states over the March military intervention of Saudi Arabia in Bahrain and the busting of an alleged Iranian spy ring in Kuwait.

On Sunday, Iran expelled three Kuwaiti diplomats after that country said it would expel three Iranian diplomats who have been accused by Kuwait of being part of an alleged Revolutionary Guards spy ring. Iran denies the allegations.