NEW DELHI, India (AP) _ A defecting Afghan army officer who claims he had access to top-level security records said today that a Soviet general is President Najib's top adviser.

''His name is Gen. Verinikov. He is a three-star general. He comes every day without failure to the headquarters meeting in Arg Palace and whatever he says is never rejected,'' Mohammad Kakar Neda told a news conference.

In Moscow, an officer at the Soviet Defense Ministry said the general had served as Najib's military adviser but left Kabul in February when the Soviet Union announced that the last of its troops had returned home from Afghanistan.

''Since the withdrawal of our forces, he's been here in Moscow and he hasn't been advising anyone,'' the officer said, speaking on condition of anonymity.

He identified the general as Valentin I. Varenikov, a different spelling than the one given by Neda, and said he had ''one big star,'' denoting a higher rank than the three stars described by Neda. The officer said Varenikov was now the main commander of Soviet land forces.

Neda, who can be located only through intermediaries because he said he is concerned about his safety, could not be contacted immediately for further comment.

Western and Afghan observers in Kabul have said scores of Soviet advisers, both military and civilian, remain in Afghanistan.

A well-placed source said that a Soviet colonel was seen at Kabul airport in March. When recognized, the colonel said he had retired from the military and returned to Kabul as a civilian adviser, the source said on condition of anonymity.

Neda said he himself was promoted to brigadier general shortly before coming to New Delhi on March 23.

He said he served as secretary to the Afghan Supreme Military Council for the Defense of the Homeland, a 20-man group headed by Najib.

The council assumed top government authority when Najib declared a state of emergency on Feb. 18, three days after the Soviet Union announced it had ended its nine years of direct combat support for the Afghan army in the war against U.S.-backed Moslem guerrillas.

''Najib's support in the party is not very good, and if he did not have Soviets attached to him, he would not be able to survive,'' Neda said. ''Right now he has a very strong Soviet support group, and with this group is Gen. Verinikov.''

Neda said he had never heard the Soviet general's first name but had seen him and knew that he met top Afghan military officials.

Neda said he also had seen Afghan military documents that said 40,000 soldiers defected from the 250,000-man army between Sept. 1 and March 1.

Other papers reaching the council said Najib's government had ''nominal control'' of just 4,000 of Afghanistan's officially recorded 36,000 villages and 10,000 other villages were ''destroyed and uninhabitable'' after a decade of civil war, Neda said.

The rest of the villages, he added, were controlled by or sympathetic to the mujahedeen (Islamic Holy Warriors) who have been fighting to topple Kabul's Soviet-style government for the past decade.

Neda said he was a full member of the Supreme Military Council. His name, however, was not on the list of members announced by the government in February.

''That is correct,'' he said in response to a reporter's question. ''In the beginning of March, I was promoted to this post.''

His assertion could not be independently confirmed, but the Kabul government has a history of making appointments without public announcement.

Neda said he had been one of four secretaries attached to the Supreme Defense Council and was elevated to full council membership as a result of long-time association with Vice President Abdul Rahim Hatif, a senior council member.

The 47-year-old Neda said he was not a combat soldier and had spent most of his military career in engineering and construction work before rising in the military bureaucracy.

Neda's remarks were translated by Said Mohammad Maiwand, a self-exiled Afghan who opposes the Najib government and is at odds with most mujahedeen factions as well.

Neda, however, understood some English and said he spent part of 1978 in the United States on a military training course, studying English at San Antonio and engineering at Fort Belvoir, Va.