All the communist countries of Eastern Europe put obstacles of one sort or another in the way of Western reporters. But few go to the lengths of Romania, which recently assigned an estimated 75 secret police cars and 150 agents to keep track of a single visiting journalist.

During a 10-day visit to Romania, my notebooks became so full of the license numbers of policed cars tailing me that eventually I gave up writing them down. Plainclothes agents were stationed in restaurants, hotel reception areas, even behind bushes and telegraph poles.

Fresh teams of radio-linked patrol cars lay in wait outside every major town -- and there was also a regular rotation of personnel between day and evening shifts.The secret police escort never numbered less than two cars and frequently there were as many as three or four to cover all possible routes at highway intersections.

The effort appeared designed to prevent any unauthorized contacts with ordinary Romanian citizens. But it also provided an excellent first-hand insight into the workings of one of the most feared secret police organizations in Eastern Europe today.

This month another Western correspondent, Peter Ristic of the London Observer, was detained at Bucharest airport for three days after being refused permission to enter Romania. While waiting for the next plane back to Belgrade, the Yugoslav capital, he was kept in a small room under constant guard and not allowed to contact the British Embassy.

After being expelled, Ristic said his coverage last year of Romanian dissidents including an independent trade union movement appeared to be the reason for his being declared "persona non grata" by the authorities. He added that when he protested at being locked up, a Romanian guard threatened to place him in handcuffs.

The harassment of Western correspondents is a reflection of the extreme sensitivity of President Nicolae Ceaucescu to negative publicity abroad about human rights violations in Romania. His government has made a major effort to convince the West that it is fulfilling all its obligations under the 1975 Helsinki declaration on security and cooperation in Europe, which comes up for review in Madrid later this year.

Contact between ordinary people and foreigners is controlled more closely in Romania than anywhere else in the Soviet Bloc. Western diplomats stationed in Bucharest complain that informal contacts with Romanian officials have to be channeled through the protocol department of the Foreign Ministry. Invitations to functions are frequently accepted and then turned down at the last minute.

Several years ago, the Romanian government passed a law forbidding foreigners from spending the night in Romanian homes. The measure appeared largely directed against Hungarians and Germans visiting their co-nationals in Transylvania, but it has also prevented Romanian families from earning extra money by renting out rooms to foreign tourists.

The security services, which together with the uniformed militia form part of the Ministry of the Interior, have posts in every town and village in the country. They can also count on a network of hundreds of thousands of informers in this Balkan nation of 22 million people.

The writer Paul Goma, who launched an appeal for greater respent for human rights in Romania, once joked that there were only two people in the whole country unafraid of the secret police: "President Ceaucescu and myself." Soon after making that joke, he was detained by the security services for a gruelling month-long interrogation. He now lives in France.

For the foreign journalist, protected by his profession, the attentions of the Romanian secret police are annoying rather than frightening. They can also be amusing as attempts by agents to remain inconspicuous render them very conspicuous.

In contrast to the friendly helpfulness of ordinary Romanians, plain-clothes policemen are identifiable by their monosyllabic negative grunts when engaged in conversation. When pursued themselves, either on foot or by car, they tend to flee in the opposite direction as fast as possible.

Agents assigned to follow me resorted to a variety of ruses to conceal their identities. The rapid wigchanging technique of one woman agent was impressive as was the sense of devotion displayed by a male agent during an orthodox church service in a Moldavian village.

Some agents succeeded by giving themselves away by theatrical behavior. One flattened himself dramatically against the wall of an alley as I drove past. Another attempted to hide behind a concrete electricity pylon rather too narrow for his wide girth. A third replied with an overincredulous "Who me?" in English when accused of listening to telephone calls from the hotel reception desk.

The most ingenious device was employed by a male agent stationed at a bus stop on a deserted country road between Alba Julia and Deva in central Romania. In an apparent attempt to prove his status as an ordinary Romanian citizen, he hitched a lift from a passing truck.

Followed round the corner, the agent was seen getting out of the truck and walking toward two waiting cars. Apparently panicking, he ran for the cover of a nearby woods as his colleagues roared off in their cars to a screech of tires. None of them was ever seen again -- and a fresh team of undercover agents was sent out from the next town.