Former president Shimon Peres remained in serious but stable condition on Wednesday morning after suffering a severe stroke Tuesday night, said Sheba Medical Center in Tel Hashomer Director Yitzhak Kreiss.Later on Wednesday Kreiss said in a press conference that the senior statesman's condition had "somewhat improved." Kreiss said that doctors had opted not to perform surgery on the retired statesman at the moment.The veteran 93-year-old politician had just last week undergone placement of a cardiac pacemaker at the hospital and was discharged in good condition. He returned to the hospital for a checkup, but suddenly suffered a stroke.Peres's personal Doctor Rafi Walden said that during the night he had been responsive and held family member's hands. Ayelet Frish, the former president’s communications consultant, said Tuesday that Peres “woke up this morning at his home with palpitations and a feeling of constriction in his chest.”Peres had complained of chest pains and had difficulty breathing. His personal physician is also his son-in-law, Prof. Rafi Walden, who is a leading surgeon and deputy director of Sheba. After hearing of his complaints, he took him to the hospital for tests.It was learned late on Tuesday that he suffered from a hemorrhagic stroke, which occurs when a weakened blood vessel ruptures (usually caused by uncontrolled hypertension).It is also unknown whether there was any connection between the insertion of the pacemaker – to ensure a regular heartbeat – and the stroke.Sheba director-general Prof. Kreiss said that Peres, in the intensive care unit, had suffered “lots of bleeding.” “The 9th President of the State of Israel, Shimon Peres, suffered a major stroke today," said Kreiss. "He is being treated by the best doctors in the hospital from across the medical fields. He underwent a number of scans and is currently sedated and intubated. "He is in intensive care and we are monitoring him constantly. In the coming hours we will conduct further examinations and will update regarding his condition,” the doctor noted. Shortly after, Peres’ son Chemi asked people to pray for his father as he spoke to reporters outside the hospital."These are difficult hours for me and my family. I want to start by thanking the medical staff at Tel Hashomer who are assessing my father and consulting with the family. There will come a time when we will need to take some decisions. Everything is dependent on how things develop and we don’t know more than that at present."He added: "The family are all gathering at the hospital and we will continue to update. We are receiving a huge number of messages from Israel and abroad from all our friends who are surrounding us with love and care. I want to tell them all that there was nothing more important to my father than Israel and its people. My father is one of a kind, I am praying for him and ask all those that pray to continue to pray with us. We thank everyone for your love and care.” Prime Minister Benjamin Netanyahu wrote on Twitter that he and the entire people of Israel love him and hope he has a complete recovery.Opposition leader Isaac Herzog wrote on Twitter that he hopes Peres recovers quickly. He said he hopes Peres will soon “resume making his clear, smart and enlightened voice heard.”President Reuven Rivlin said: “I am following with concern the updates from the hospital, and pray together with the entire people for my friend Shimon’s recovery.”News of his falling ill aroused much concern, with calls from all over the country and the world. Initially, the office of the ninth president said Peres was “conscious and in stable condition, but suddenly, his condition took a turn for the worse. It was announced that he was put under sedation to ease the continued treatment, and was connected to a respirator.He was then taken for a computerized tomography (CT) scan of the brain for a “complete and accurate assessment of his condition,” the spokeswoman of his office said.The longest serving of all of Israel’s public servants, Peres completed his seven-year term of office as president of the State of Israel just two weeks shy of his 91st birthday.Born in Wiszniewo, Poland, he was one of the founders of the Labor-Zionist Youth Movement and a member of the Hagana during the pre-state period. He became director-general of the Defense Ministry at age 29 and was a member of the Knesset from 1959 to 2007.He served in different political parties, namely Mapai, Rafi, the Alignment, Labor and Kadima.Peres spent a long period as Labor Party chairman, and held a string of government roles including two non-consecutive stints as prime minister, and over the years he was minister of Immigrant Absorption, Transportation, Information, Defense, Communications, (or Posts and Telegraphs as it was known then), Internal Affairs, Religious Affairs, Foreign Affairs, Finance and Regional Cooperation.He served in some of these positions more than once.He also had various stints as acting prime minister, deputy prime minister and vice prime minister.Peres is one of the architects of the Oslo Accords. In recognition of his work for that famous agreement, he was awarded the Nobel Peace Prize in 1994, an honor he shared with former Palestinian Authority chairman Yasser Arafat and former Israeli prime minister Yitzhak Rabin.Gill Hoffman contributed to this report.