The Iraqi Army tightened its stranglehold on the Iranian city of Abadan today, sending troops and armor to within sight of the burning oil refinery in a northern pincer movement and cutting off all but one supply line to the besieged city.

The Iranians continued to strike back, however, sending Phantom fighter-bombers to attack an already heavily damaged refinery in this port city and bomb Iraqi artillery positions overlooking Abadan.

Meanwhile, Iraq said two Iranian planes hit civilian targets in Baghdad and others bombed Suleimaniyah and Basra. Baghdad said its forces shot down at least two Iranian planes near Abadan and downed a helicopter in driving back an assault in an unspecified battle area.

Iraqi aircraft raided Tabriz in northwestern Iran today, killing a number of people and damaging the city's oil refinery, Tehran radio said today.

The radio also said Iranian forces took 15 Iraqi prisoners in a skirmish yesterday. It did not say where the action took place.

Another Tehran broadcast, monitored by the British Broadcasting Corp., said that Iraqi forces were driven "a few kilometers" father back from the huge refinery at Abadan last night and are five miles from the Bahmanshir Bridge. The Bahmanshir River runs just east of Abadan.

There were indications that the Iraqis are reluctant to commit themselves to a major ground offensive against Abadan, either out of fear of the political consequences at home because of the casualties they would incur, or because they have no confidence that the large Arab ethnic population there will offer tacit support.

"We could capture Abadan in two days, but why take the casualties?" a Ministry of Information official remarked. "We will be in Abadan soon enough."

Much of the information about today's fighting in the 25-day-old war came in the form of official communiques and statements from the two governments and could not be verified independently.

A small group of foreign journalists were escorted across the Karun River to within two miles of Abadan, where they could see Iraqi tanks advancing about one mile from the city. The Karun enters the disputed Shatt-al-Arab waterway at Khorramshahr.

The six journalists were taken to the front in an apparent attempt to mollify more than 50 correspondents who have been confined to Basra by Iraqi authorities.

The Iraqi forces captured a television transmitting station on the outskirts of Abadan, a city of about 350,000, which has the world's second-largest oil refinery.

An armored personnel carrier with 14 Iranian soldiers, taken prisoner, was seen moving from the front to the television station. The prisoners appeared relaxed, although some were tied at the hands and one was blindfolded.

"God give you strength in your work," one prisoner said to a Norwegian television correspondent. "Salaam aleikum," (Peace be with you).

The main highway running from Abadan to Ahwaz was strewn with abandoned civilian vehicles taken out of Abadan during the last two weeks of heavy bombardment by Iraqi artillery. The vehicles, including new Mercedes Benz automobiles and some trucks, were loaded with personal possessions that have been looted by Iraqi soldiers.

Iranian Phantom aircraft reportedly attacked the Iraqi pontoon bridge that was put across the Karun earlier in the week, and Iranian artillery to the rear continued to harass Iraqi positions close to Abadan.

Most of the resistance, however, was from small-arms fire and occasional raids by jeeps mounted with machine guns or recoilless rifles. The Iranian jeeps would race toward an Iraqi position, fire off a few rounds and then retreat to safety.

According to accounts reaching here, the Iraqi Army has cut the Khorramshahr-Ahwaz highway and the Abadan-Ahwaz-Tehran highway, and there were many abandoned cars and trucks near the river crossing. The six oil pipelines that formerly linked the Abadan refinery with Ahwaz, the communications center of Dezful and Tehran, are burning in four places near the crossing.

The barren desert plain was sprouting funnels of smoke all around. In the background were the towers and pipes of the Abadan refinery, which has been aflame since the early days of the war.

Meanwhile, the National Iranian Oil Co. radio called on the people of Abadan and Khorramshahr "to remain actively on the scene" and remain ready to oppose any aggression.

The radio added, "It is up to you Moslem and revolutionary people of Abadan and Khorramshahr to be completely prepared -- now more than any other time -- to defend Islam and the Koran and to be prepared to attack the army of the faithless and oppressors."