BEIRUT, Lebanon (AP) _ Rival Christian forces battled with tanks in burning east Beirut and fought with daggers and bayonets for control of a key coastal town Sunday. Police said 210 people have died in the savage six-day showdown.

Gen. Michel Aoun's forces claimed they captured the town of Dbaye, 5 miles north of Beirut, from Christian warload Samir Geagea, and Aoun's Channel 5 TV station showed paratroopers occupying what it said was Geagua's Lebanese Forces base there.

But Geagea's militia said the defenders repulsed 10 tank-supported assaults by the paratroopers and forced them to retreat after hand-to-hand battles with bayonets and daggers.

Aoun sent artillery, tanks and troops to seize the militia's headquarters in east Beirut, but the militiamen held off the fierce bid to solidify Aoun's control of the devastated Christian enclave in this ruined city.

Two oil tanks and scores of buildings set ablaze in the fighting burned out of control. Pillars of flame shot skywards and thick clouds of black smoke shrouded the area.

Police said 210 people have been killed and 935 wounded, mostly civilians, in the deadly fighting that began Tuesday in the Christian enclave, where an estimated 1 million people live. Both sides ignored appeals by clergymen to end ''the senseless, horrific massacre of the innocents.''

An estimated 500,000 people cowered in basements and bomb shelters as shells - as many as one round each second - rained all night long from Aoun's mountaintop positions east of the city.

At dawn, Aoun's tanks advanced through the northern Dora industrial district and the northeastern Rummaneh quarter, police said.

The offensive was an apparent make-or-break attempt to crush Geagea's Lebanese Forces and become the undisputed leader of the Christian enclave north of Beirut.

In the cold, dank underground shelters, food, water and powdered milk supplies ran out, radio stations said. Electricity has been cut off for nearly a week.

Hundreds of shells and rockets have landed in Moslem west Beirut, which has not been involved in the latest power struggle. At least 25 people have been killed and 105 wounded in the Moslem sector since Tuesday.

To add to Beirut's woes, a four-hour gunbattle broke out between rival Shiite Moslem factions in its southern slums Sunday.

Police said four people were killed and seven wounded before Syrian troops moved in to separate the Iranian-backed fundamentalist Hezbollah, or Party of God, and the Syrian-allied Amal militia.

They have been vying for control of Lebanon's 1.2 million Shiites, the country's largest sect, for more than two years.

Cease-fire appeals by the Red Cross, a group of 16 Lebanese parliamentarians and the Vatican's representative in Lebanon, Papal Nuncio Pablo Puente, were ignored. France also appealed for a cease-fire and said it was prepared to send medical aid to Lebanon quickly.

Six earlier truce accords failed to stop the fighting, among the worst in the Christian sector since Lebanon gained independence from France in 1943.

Shells hit churches, hospitals, schools and apartment buildings. The Christian Voice of Lebanon radio station broadcast assurances from nuns to anguished parents that about 60 children trapped in a school were safe.

Both Aoun and Geagea are Maronite Catholics, the dominant Christian sect.

The general, appointed head of an interim military cabinet in September 1988 by outgoing President Amin Gemayel, considers himself the sole legitimate authority in Lebanon.

Geagea has been the Christians' standard bearer in the nearly 15-year-old civil war against the Moslems.

Aoun has 20,000 troops. Geagea's heavily armed militia has 6,000 fighters and 30,000 reservists.

Aoun's inability to crush Geagua has triggered speculation that he risks being ousted by his troops if he does not deliver a quick victory.

At least 1,000 have defected, 600 to the Lebanese Forces and 400 to Gen. Emile Lahoud, the army commander named by Syrian-backed President Elias Hrawi, military sources reported.

Hrawi, another Maronite, was elected by Parliament Nov. 24 with a mandate to oversee a peace plan brokered by the Arab League in October.

He fired Aoun as interim prime minister and army commander, but Aoun refused to quit.

Aoun rejected the peace accord because it fails to guarantee the withdrawal of 40,000 Syrian troops from Lebanon. Aoun considers the Syrians, who entered Lebanon in 1976 under an Arab League peacekeeping mandate, to be an army of occupation.

Syria backs the Christian-Moslem government of Hrawi.

Hrawi said Sunday that if the fighting persists he ''will issue orders for intervention in the interest of all citizens.''

That indicated he was prepared to send Lahoud's 22,000 Moslem troops against Aoun.