Hopes for a temporary Moslem holiday cease-fire in the 27th day of the Persian Gulf war collapsed today as Iraqi forces reportedly crushed an attempt by the Iranian defenders of Abadan to break out of the encircled oil refinery city.

Having achieved superiority on the ground, the Iraqis for the first time threw their tiny Navy into the war, sending Soviet-built Osa gunboats equipped with Styx surface-to-surface missiles down the disputed Shatt-al-Arab waterway to interdict Iranian Navy vessels trying to move up the channel to relieve Abadan.

An Iraqi military communique claimed that Iraq's forces had killed 52 Iranian soldiers and captured 17 in the ground fighting to repel a counterattack in Iran's oil-producing Khuzestan Province. The communique said three Iranian tanks were destroyed and three aircraft shot down. It admitted the loss of 16 Iraqi soldiers, one armored personnel carrier and four vehicles.

In tehran, meanwhile, authorities reported "hand-to-hand fighting" in the Iranian port city of Khorramshahr for the third day. The official Tehran radio said the city's commerical and residential districts were under "heavy rocket and shell fire." The radio also reported artillery exchanges at Abadan and "heavy fighting" far to the north at Gilan-e-Gharb, about 25 miles inside Iran.

Later, Iran's official Pars News Agency reported that the Iraqi Army was intensifying efforts to encircle Abadan and Khoramshahr to "seize them by a sudden assault." The radio also quoted the governor of Abadan and the commander of the Khorranshahr Revolutionary Guards as saying that the defenders' morale was high but that they were hoping for more and swifter help from the Iranian Army and other citizens.

According to an Iraqi communique, Iranian Phantom jets bombed a border village about 180 miles north of the Iraqi capital, killing one civilian.

Another statement from Baghdad charged that Iranian artillery fire sank a Panamanian merchant vessel in the Shatt-al-Arab.

Slicing through the normally placid green waters of the Shatt-al-Arab, where sea birds gracefully dive for fish, the Iraqi gunboats braved a gantlet ofIranian fire on their way to the mouth of the waterway as their crews manned battle stations.

Later, Radio Baghdad claimed that the Navy had dispersed the Iranian flotilla and captured one of the Iranian vessels.

Pakistani President Mohammed Zia ul-Haq, acting as a mediator for the 40-nation Islamic Conference, has sought to have both Iraq and Iran agree to a four-day cease-fire to mark the Aid al-Adha, the joyous Moslem feast of sacrifice ending the annual pilgrimage to Mecca.

Although the Iraqis had indicated willingness to accept such a cease-fire, which would have allowed the departure of about 100 foreign freighters trapped on the Shatt-al-Arab by the fighting, Iran has refused any cease-fire as long as Iraqi troops are on its soil. On the other hand, Iranian President Abol Hassan Bani-Sadr has said he has no objection to a U.N.-sponsored truce on the Shatt-al-Arab under which ships would be allowed to leave flying the U.N. flag. But Iraq has insisted that any departing vessels fly the Iraqi flag to symbolize Baghdad's claim to the waterway.

With its Army poised on the edge of Abadan, Iraq continued to send troops and armor across a precarious pontoon bridge over the strategically important Karun River north of Khorranshahr. Behind the reinforcements, which churned up huge clouds of dust across a roadless plain during their advance, came heavy road graders and earth-moving equipment in an effort to lay down crucial all-weather roads. These are aimed at beating the approaching rainy season, which could turn the communication lines into impassable muddy bogs.

It was clear that after weeks of making exaggerated claims of having captured Khorramshahr and Abadan, the Iraqis in the last few days have finally managed to surround the two cities, cutting them off to any further reinforcement and resupply. The Iranian defenders, however, were holding on tenaciously and continuing their do-or-die defense of their cities.

Hojatoleslam Mohammed Ali Khamenei, the religious leader of Tehran, admitted at Friday prayers that the Iraqis had cut off Abadan. His admission came as Tehran radio claimed that the people of Abadan had turned the city into a "fortress and were preparing for hand-to-hand combat, digging trenches for street defenses."

The Abadan situation seems set for a repeat of the battle of Khorramshahr, the vital cargo port city that the Iraqis have still to capture after almost four weeks of artillery and tank assaults. The Iraqis evidently have miscalculated the determination of the Iranian defenders, made up of Revolutionary Guards and elite armored and commando troops.

The Iraqis have yet to show any inclination to mount a direct assault on any of Iran's cities. Instead, they have preferred to sit on the outskirts and try to pound the enemy into submission with relentless artillery barrages.

Those tactics, have bogged down the conflict into a war of attrition that could, in the long run, become a political liability to Iraqi strongman Saddam Hussein, Western observers believe. After almost four weeks of war the Iraqi forces have yet to capture any of their initial strategic objectives.