AMMAN (Reuters) - King Hussein of Jordan completed a bone marrow transplant on Tuesday to treat a relapse of cancer but will remain under close monitoring for two weeks, Jordan‘s envoy to the United States said. Ambassador Marwan Muasher, speaking from the Mayo Clinic where the king was admitted for urgent treatment last week, said the 63-year-old monarch was "holding up very well" after two bone marrow infusions on Monday and Tuesday. But he said doctors were keeping an extremely close watch on the king, a heavy smoker fighting his second bout of cancer in seven years. "He‘s going to go through a difficult period for the next two weeks. He will be under close monitoring in case of complications either from the bone marrow or from the chemotherapy," Muasher told Reuters by telephone. King Hussein, the Middle East‘s longest-serving ruler, shocked Jordanians last week by sacking his brother as heir to Jordan‘s Hashemite monarchy after three decades of grooming and replacing him with his inexperienced eldest son Abdullah. The next day he was rushed back to the Mayo Clinic, just a month after being discharged from six months‘ treatment for non-Hodgkins lymphoma, a type of cancer. Doctors said he had suffered a relapse and prescribed more chemotherapy followed by the bone marrow transplant. Muasher said first indications were positive but that it was too soon to say if the cancer had been successfully treated. Muasher said the king was regularly in touch with Amman, where Crown Prince Abdullah has been plunged into affairs of state, meeting high-level figures including U.S. Secretary of State Madeleine Albright and Saudi Arabia‘s Defence Minister Prince Sultan bin Abdul-Aziz. King Hussein has ruled Jordan since 1952 when he came to the throne as a teenager. Only a small minority of Jordanians have lived under any other ruler. He is credited with maintaining stability during a 47-year rule over a fragile kingdom and has come to be seen as a pivotal figure in the U.S.-led search for Arab-Israeli peace. His sudden and apparently bitter dismissal of his brother shocked Jordanians but Jordan‘s allies, including the United States, have stressed they would support Abdullah, a career soldier who marked his 37th birthday on Friday, and believed he would continue his father‘s policies.