Aras an Uachtaran has confirmed that Sabina Higgins visited an elderly peace activist in Limerick jail last weekend.
The wife of President Higgins went to see Margaretta D'Arcy who was jailed for refusing to sign a bond to stay away from unauthorised areas of Shannon airport.
The 79-year-old, who is undergoing treatment for cancer, is serving a three-month sentence for illegal incursion on the runway at Shannon Airport in October 2012.
Ms D'Arcy - a writer and a peace-activist - was protesting against the use of Shannon by the US military.
Her sentence was activated last week when she refused to give a commitment to stay away from unauthorised zones at the airport.
Michael D. Higgins spoke at the funeral of Ms D'Arcy's husband, the playwright John Arden, in 2012.
A spokesperson for Aras an Uachtaran last night confirmed that Sabina Higgins had paid a visit to Margaretta D'Arcy at Limerick Jail on Sunday.
He described the visit as personal and private, adding the two women had known each other for many years.