ATHENS, Greece -- Soviet forces sealed the Azerbaijan republic's border with Iran Monday, stopping the flow of thousands of people out of the country, but allowing back in those already outside, Tehran radio said.
The Tehran Times, meanwhile, denied reports in the Soviet newspaper Izvestia saying Iran had supplied the Azerbaijani nationalists in the rebellious southern Soviet republic with weapons.
Soviet soldiers stormed the Azerbaijani capital of Baku over the weekend to end fighting between Armenian Christians and mainly Moslem Azerbaijani nationalists in the worst ethnic conflict confronting Soviet President Mikhail Gorbachev.
In a broadcast monitored in Athens, Tehran radio said Monday that Soviet soldiers took up positions at the border near the Iranian town of Bileh Sowar and the Caspian port of Astara.
'Following four days of movement back and forth by Moslems of the Soviet Union to Iran, as of this morning military forces have taken up positions on the border and are strictly stopping them there,' the radio said.
'Only those people from Soviet Azerbaijan who are already in Iran are being given permission to return, with detailed checking,' the radio said.
Thousands of people began crossing the border into Iran from Soviet Azerbaijan as of Thursday at Bileh Sowar and Astara, about 300 and 225 miles northwest of Tehran.
By Sunday, Iran's official Islamic Republic News Agency said some 20,000 people had come over, mainly from Jalilabad and the Soviet Caspian towns of Lenkoran and Astara, but the bulk returned home after staying some hours and only a few hundred stayed behind.
The visitors, many of whom reportedly came to Iran to attend prayer ceremonies on Friday, the Moslem sabbeth, included women and children, and created problems for local authorities, who were hard put to find accommodation for them.
The Soviet Azerbaijanis apparently crossed without going through border formalities either on the Soviet or the Iranian side. The news agency said Soviet helicopters began flying over some border crossing points over the weekend.
Soviet forces sealed the border two days after military forces began moving into Baku and Lenkoran, where the local people set up barricades to stop them from getting in.
Late Sunday, Iranian President Akbar Hashemi-Rafsanjani chaired a meeting of the Iranian Cabinet, which expressed regret about the use of force in Soviet Azerbaijan, the news agency said.
On Saturday, Rafsanjani met with Iran's National Security Council to discuss the situation in Soviet Azerbaijan, which is adjacent to an Iranian region with the same name.
Iran's ruling clerics and the official media have also expressed concern about Soviet military action in Baku, the Azerbaijani capital.
The Iranian Foreign Ministry Sunday expressed 'deep regret over such improper measures and seriously wants the Soviet government to halt violent encounter with the people of Azerbaijan.'
As of early January, scores of people from Nakhichevan crossed the Aras River to enter Iran at the border towns of Poldasht and Jolfa. Nakhichevan is an enclave of Soviet Azerbaijan sandwiched between the Armenian republic and Iran.
Most reportedly crossed back into the Soviet Union, some in boats, carrying copies of the Koran, the Islamic holy book, and other printed material with them.
Apart from the Armenians, the people of the Soviet republics adjacent to Iran are mainly Moslems, and have been exposed over the past 10 years to religious broadcasts on Iran's state radio and television.
In June 1989, Iran and the Soviet Union signed an agreement to allow people living in the border areas on both sides more freedom of cross-border trade and travel. Details of the agreement were still to be worked out.