KARACHI.-Amid signs of a deterioration in the already hostile relations between India and Pakistan, Pakistan charged that Indian fighter planes had violated Pakistani air space today on two occasions.

The Pakistani radio reported that Indian aircraft had flown over the Rangpur district of East Pakistan in the morning and again at noon. The broadcast did not identify the type of aircraft allegedly involved.

It was the first time in the present crisis that Pakistan had charged that Indian planes had violated her air space.

In another development, it appeared that negotiations had been nearly completed for the repatriation of Pakistani diplomats from Calcutta in India and of Indian diplomats from Dacca in East Pakistan.

Pakistan's Deputy High Commission, or consulate, in Calcutta has been the center of a diplomatic war since the predominantly East Pakistani staff took it over on April is and transformed it into a mission of the newly- proclaimed provisional government of Bangla Desh-the Bengal Nation.

The Pakistani Government at Islamabad sent another official to take charge of the mission but the East Pakistanis continued to occupy it and Indian authorities declined to dislodge them.

Pakistani authorities in Dacca responded by placing Indian diplomats there under virtual house arrest and loyal Pakistani officials in Calcutta were similarly restrained by India.

During the last few days, the Soviet Union, which is friendly with both Pakistan and India, apparently has mediated certain aspects of the dispute. The Pakistani Government announced today that India had been asked to allow an Iranian plane to evacuate Pakistani diplomats from Calcutta and that the Soviet Union had been asked to provide air evacuation of Indian diplomats from Dacca.

The proposed exchange was apparently arranged by Moscow.

INDIA ACCUSED

There was speculation here that the Soviet Union was involved in far-reaching mediation efforts to end armed clashes between Indians and Pakistanis. A precedent was established in 1965, when the Soviet Union arranged an armistice in the brief war between Pakistan and India over the disputed Rann of Cutch area.

But since March 25, when Bengali separatists in East Pakistan demanded complete secession from West Pakistan, West Pakistan has charged that India is trying to destroy Pakistan as a nation,

The Pakistani Government says that the population of East Pakistan mostly favors national unity and that only the infiltration of Indian troops and supplies has kept the rebel forces alive.

West Pakistan newspapers today quoted Government sources as denying that large numbers of refugees were fleeing East Pakistan to neighboring India.

Statements attributed to officials in the Pakistani capital of Islamabad, said that the majority of persons who had crossed from East Pakistan into India since March 25 were Indian military infiltrators who had been sent to cause trouble in Pakistan.

According to the Pakistan Government,these and local "miscreant" followers have been crushed by the Pakistani Army and survivors are returning to West Bengal Province in India.

PROBLEM FOR INDIA

The Pakistani statement followed reports from India that roughly one million Pakistani refugees had arrived in India, posing a severe economic problem for the New Delhi Government.

The Karachi morning newspaper Dawn quoted Pakistani Government officials as saying:

"West Bengal in India under the best of circumstances has a large floating population and hundreds of thousands sleep on the pavement in Calcutta as a matter of daily routine. To any unsuspecting foreign visitor these could be shown as refugees from across the border."'