The authorities in Iran's oil-rich province of Khuzestan are planning to increase the presence of security forces in the area to counter a growing wave of bomb explosions and guerrilla attacks which last night damaged an oil and gas pipeline.

The explosion blasted a pipeline carrying oil and gas from well No. 120 to a processing station near Ahwaz, setting fire to oil and gas in the pipeline but causing no damage to other installations, according to official reports.

Oil industry sources said the explosion had no effect on normal oil production and exporting activities.

The attack was the first successful strike against oil installations since guerrillas blew up oil and gas pipelines linked to the country's biggest refinery, which is in the southwestern town of Abadan, in June.

Revolutionary Guards sources in Ahwaz disclosed, however, that there had been a recent attempt to blow up unspecified facilities using incendiary devices.

Khuzestan's governor general, Adm. Ahmad Madani, said today that the wave of violence was expected following recent successful naval maneuvers in the Persian Gulf and that he did not think the situation was serious. "It is not very important, we can keep control of it," he told reporters.

He added, however, that he was seeking to increase the numbers of Revolutionary Guards from about 1,000 to about 1,500.

In a separate incident today, one person died and another was seriously injured when a mine exploded under their vehicle on the road near Ahwaz.

A total of three attacks were mounted on two microwave communication stations by groups of unidentified gunmen last night. The violence followed by only a few days an attack on a communications center between Ahwaz and the southern port town of Khorramshahr, which temporarily served outside links with Khorramashahr and the oil industry center of Abadan.

The vilence spread last night to Abadan where gunmen again clashed with security guards.

Meanwhile, three persons are reported to have died from the bomb that exploded yesterday in the Khorramshaar's bazaar, leaving more than 30 people injured. The bomb was said to have been similar to one that exploded two days earlier under a train traveling from Khorramshahr to Tehran, killing eight and injuring 16.

Madani said the bombings were the work of ethnic Arab groups who earlier this summer challenged the authorities with demands for greater autonomy. He added that guerrillas were backed by foreigh interests and suggested that the Iraqi authorities were involved at least indirectly.

Several persons have been executed by the revolutionary authorities in the last two weeks. At last five of them are believed to have been Iranian Arabs. The charges against them were possessing and distributing arms and working for foreign interests. Eight men executed after the train bombing were charged with receiving guerrilla training abroad.