Doctor of Kremlin critic Alexei Navalny, Anastasiya Vasilyeva, was not allowed to enter the prison grounds where the opposition politician was held.
Vasilyeva said she had applied for a meeting with the head of the prison, however the security in front of the prison did not allow her to meet Navalny or the local medical staff.
Russian police stepped up security at the prison holding Kremlin critic Alexei Navalny on Tuesday as his supporters prepared to stage a protest outside the facility to demand that authorities give him proper medical care.
Navalny, 44, a prominent opponent of President Vladimir Putin, announced a hunger strike last week in protest at what he said was the refusal of prison authorities to treat him properly for acute back and leg pain.
A group of his allies said they would protest at the prison in the town of Pokrov 100 km (60 miles) east of Moscow from Tuesday unless he saw a doctor of his choice and was given what they regarded as proper medicine.
Prison authorities say his condition is satisfactory and he has been provided with all necessary medical care.
Late on Monday, his allies said the protest would go ahead after Navalny said he was continuing his hunger strike, although he had a high temperature and bad cough and three inmates in his ward had been hospitalised with tuberculosis.