Four Greeks are undergoing medical tests after having frequented a London hotel or restaurant that were visited by former Russian spy Alexander Litvinenko before he fell ill and died from radiocative poisoning, authorities said on Saturday.

Urine and blood samples from the four people, who were not identified, were sent to the Demokritos state-run nuclear center in Athens, Deputy Health Minister Thanassis Yiannopoulos said.

“Results are expected in the next few days,” he added.

According to some reports, three of the four people are from the Ionian island of Corfu.

Yiannopoulos also described as “annoying” the lack of information from British authorities on many aspects of the case.

Officials said that the number of Greeks who had been to the hotel or sushi restaurant and were expected to undergo examinations was likely to increase in the coming days.

The head of the Greek Atomic Energy Commission (GAEC), Leonidas Kamarinopoulos, told AFP that almost 500 Greek passengers who had traveled on two British Airways planes in which radioactive traces were subsequently found had telephoned the GAEC.

Around 2,000 Greek passengers traveled on about 40 flights between London and Athens between November 4 and 26, according to Greek authorities.