The Ethiopian military government announced Saturday the mobilization of more than 50,000 additional troops belonging to local militia units throughout the country, amid numerous indications that the seven week-old war with Somalia is growing steadily worse and that its armed forces are now in serious difficulty.

Late last night, the government issued a statement saying that "Regular troops of Somalia, supported by troops from certain reactionary Arab regimes and having deployed tanks and artillery, are making advances to capture Dire Dawa, Harrar and Jigjiga" in eastern Ethiopia.

It called on all civilians living near the eastern war front to join the regular army and militia force in defending Ethiopia against the "arrogant armed invasion" from Somalia and to prepare "fortified defense positions" in every locality.

It also ordered all army veterans under 60 years of age to report for duty and all truck and bus owners to put their vehicles immediately at the government's disposal.

The appeal for a further mobilization of the country's manpower and resources to combat both the threat from Somalia and that from Eritrean separatists in the north gave the current situation a sense of national crisis that had not heretofore existed here.

Today, the capital was calm and busy as usual. But Ethiopians everywhere were discussing the latest war developments with obvious concern and listening to the state radio, which is now playing marital and patriotic musics interspersed with news reports 24 hours a day.

So far the government has neither confirmed nor denied the fall of jigjiga to somali forces. But it admitted for the first time that enemy troops are "making advances," an apparent admission that Ethiopian defense of the town where the main battle of the war is now taking place had been broken.

Informed sources here said that Jigjiga fell Wednesday, after five days of extremely fierce fighting in which both sides are believed to have sustained heavy losses in men and materiel.

The callup of tens of thousands of local militamen, in addition to the 100,000 already mobilized, seems to indicate that the Somali offensive has not been halted and that Harrar and Dire Dawa are now in real danger.

The war, which began in earnest July 23, is being fought over the Ogaden Region of southeastern Ethiopia, to which Somalia has long laid claim. After unleashing irregular guerrillas belonging to the Western Somalia Liberation Front, the Somali government has now apparently committed a large part of its regular army to the seizure of the 200,000-square-mile piece of semi-desert land.

However, Somalia continues to deny that its regular army is involved in the fighting and contends that only the front is responsible for what is happening in the Ogaden.

Wednesday, the day jigjiga is reported to have fallen, the Ethiopian government flew a party of foreign correspondents to Dire Dawa, 300 miles cast of here, and showed them nine disabled Somali T-55 tanks involved in an attack on that town Aug. 16-17. There was no indication during the trip that Jigjiga, 100 miles farther east, was falling, although reinforcements were being flown in to bolster the defenses of Dire Dawa, an important railroad junction town.

The three directives issued last night by the National Revolutionary Operations Command, a special body set up to take charge of the war effort, called upon civilians living in the vicinity of three threatened towns in eastern Ethiopia to rise up and "fight along the rivers, in valleys, mountain terrains and open fields" to repel the invaders.

Although thousands of volunteer army veterans have already been mobilized, it was the first time the government has ordered all retired members of the armed forces and police to report for duty. Both the veterans and truck and bus owners were asked to come at once.

Later today, the government issued a fourth directive calling on defense squads in factories and offices here to send as many of their militiamen as possible to the headquarters of the National Revolutionary Operations Command. There are 10,000 to 20,000 such militiamen in and around the capital.

The same directive called on the peasant associations in the provinces of Shoa (central Ethiopia), Kaffa (western Ethiopia), and Arussi (southern Ethiopia), to send all armed or trained militiamen not needed for the defense of the revolution against "reactionaries" to the command's regional headquarters at once.

It is hard to calculate just how many additional troops this will give the government, but Western observers here estimated that it might reach more than 50,000.

Last spring, the military government formed a special militia force of 100,000 men to reinforce the regular army, which itself has expanded from 40,000 to around 70,000 with the addition of three new divisions in the past two years.

Altogether, it now has mobilized more than 200,000 men to fight in the Ogaden against the Somalis, in northern Ethiopia against Eritrean separatists and in western Begemdir Province against anti-Marxist elements seeking to overthrow the government.