he war over casualty figures resulting from the Israeli invasion of Lebanon has broken out, predictably, with each side accusing the other of gross distortions of the truth.

In the center of the battle is the International Committee of the Red Cross, the Swiss-run relief organization, which has 55 delegates spread out through the country now.

Press reports here today said Israeli Health Minister Eleazar Shustak had accused the International Red Cross of "wicked slander" and of publishing "false casualty figures throughout the world" in order to "defame the Israeli Army and damage Israel's reputation abroad."

The Israelis claim only 50 civilians died in the fighting in Tyre and 400 in Sidon with 450 wounded or sick in hospitals in the south and 400 others taken to Israel for treatment.

They also say there are only 20,000 homeless in areas under their control.

It was not clear from press reports whether these Israeli figures included Palestinians or were just Lebanese civilians.

Ten days ago, the Lebanese police said the number of persons killed since June 4 was 9,583 with 16,608 wounded.

The estimates of the death toll in Sidon alone, provided by the Lebanese Red Cross, have ranged from 1,000 to 2,000 with 3,000 to 4,000 wounded.

The Palestinians have given much higher estimates of the dead and injured.

Meanwhile, the Lebanese government asked the United Nations Food and Agricultural Organization in Rome on June 15 for enough food and relief supplies for 600,000 persons for a six-month period. This figure has been taken as an estimate of the total number of war refugees, or displaced persons.

The discrepancy in figures is considerable, but the International Red Cross says the only number for which it is partly responsible is the 600,000, which Francesco Noseda, head of its delegation, says came from the Lebanese Red Cross during the first days of fighting.

Noseda heatedly denied that the 10,000 figure for the death toll came from his office. He said the only figure the International Red Cross provided during the fighting was the toll of 47 dead and 247 wounded in Tyre.

"We did not mention here any figure approaching 10,000," Noseda said, adding that it would take weeks or months before any casualty figures could be established.

He said many of those initially displaced by the fighting have gone back home, particularly around Sidon, where about 300,000 persons had fled the city and its suburbs during the height of the fighting.

"Two hundred thousand was not far from reality at the time of the war, but it doesn't correspond to the reality today," Noseda said in an interview. He offered no estimate of the present war refugee population.

But the delegation's press officer, Jean Jacques Kurz, said today that there are now 10,000 displaced persons in and around Baalbek in the northern Bekaa Valley and that 8,000 of them are without water supply.

He said many of them are Palestinians who came north to escape the fighting in the south and that 3,000 of them are camping in 11 schools in the city.

The number of displaced persons appears to fluctuate enormously almost day to day depending on the scope and intensity of the fighting.

Inside Beirut, there has been a mass migration of civilians, mostly Palestinians, from the districts under daily Israeli shelling, to other sectors of the city. One relief group, Caritas-Leban, put the figure of such urban war refugees here at 70,000, but this did not appear to include the thousands who have crossed from the predominantly Moslem western sector to the Christian zone.

It appears there are more than 100,000 displaced persons just in Beirut alone and the figure may be much higher.

The International Red Cross is in a delicate position here because it must get along with the Israelis in order to maintain access to the south. Much of its relief supplies are coming in through Israel, and Noseda said today a shipload was due to arrive in Haifa shortly, where the food and other goods would be unloaded and then trucked north to Tyre and Sidon.

Other supplies are getting in from the north overland from Damascus, and there are plans now to use the port of Tripoli.

Kurz said 17.7 tons of tents, blankets, baby milk and other relief supplies were distributed here yesterday to local relief centers.

Kurz said Israel had agreed that the fourth Geneva Convention regarding the treatment of persons living in occupied territories would be applied to the Israeli-held areas in Lebanon--about one-third of the entire country.

He said practical arrangements had been worked out between the International Red Cross and Israeli authorities, allowing its delegates to have field missions in the south, maintain special communications links between them and the head office in Beirut, travel back and forth between Beirut and the south and send convoys from here.

He also said there were "roughly satisfactory stocks" in the Beirut hospitals, with medical supplies for about one week of fighting.

He said the International Red Cross had been asked by Israel to get in touch with the Palestine Liberation Organization to check whether it had any Israeli prisoners and if so to allow the Red Cross to visit them. He said talks were under way with the PLO, but he was unable to say whether it had any Israeli prisoners or whether the Red Cross would be allowed to see them.