Iran said today that its gunners were shelling a vital main highway from Kuwait to southern Iraq as Baghdad claimed its warplanes shot down two jet fighters, hammered Iranian ground forces and sank 29 enemy ships.

But despite these rival -- and largely unsubstantiated -- claims of widening conflict, for the second successive day sources with access to satellite photographs reported no change in the warring armies' positions in the Faw Peninsula.

Notwithstanding Iraqi radio promises of imminent news of "great victory," the sources said Baghdad's reinforced 7th Army had failed to dislodge Iranian troops from their six-day-old bridgehead on the western banks of the Shatt al Arab waterway near the Persian Gulf.

But the sources also discounted Iranian claims that their forces had advanced 10 miles north of Faw along the road to Iraq's southern port city of Basra.

Iraqi warplanes and helicopter gunships were reported taking advantage of the first good weather since the Iranian push began last Sunday night to "blast the hell out of" the invaders in the Faw area, according to one source.

Iraqi spokesmen said their planes flew 170 sorties between dawn and noon alone, bombing "retreating enemy troops."

Nor did the sources confirm Tehran's claims that its artillery was shelling the vital Kuwait-to-Basra road about 50 miles inside Iraq that carries the greater part of Baghdad's military and civilian imports.

"Iranian forces, by keeping the vital Safwan-to-Basra road under long-range artillery fire, have disturbed the enemy's military movement," Tehran war propaganda chief Kamal Kharazi was quoted on Tehran radio as saying.

For days Tehran's communiques have claimed -- and Baghdad's have vehemently denied -- that Umm Qasr and two smaller naval stations on the Khaur Abdallah inlet opposite Faw were under their guns.

If the claims of shelling were accurate, Iranian troops would have to have advanced well west of the Faw bridgehead, since their largest cannon's effective range is 19 miles.

The radio also quoted Kharazi as warning that "we have plans, which when implemented in the future, will totally cut off southern Iraq."

In Kuwait, Emir Jaber Ahmad Jaber Sabah chaired an emergency Cabinet session devoted to the "latest regional developments."

The emir received an Iranian envoy earlier in the week and on Thursday visited strategic Bubiyan Island, just across the Khaur Abdallah inlet from Faw.

The unscheduled visit was considered a coded message reassuring Iran that Kuwait would continue to refuse Baghdad's periodically reiterated requests to station Iraqi troops on its mud flats.

Kuwait, in the midst of celebrating its 25th anniversary as an independent state, shows little outward signs of anxiety. This surface calm in part reflects the numbing effect of six years of war.