ISLAMABAD: Prime Minister Nawaz Sharif has prolonged his stay in London after doctors discovered ‘blockage’ in one of his heart arteries during a medical check-up, reliable sources said on Thursday. In an initial medical check-up, the doctors have confirmed that Prime Minister Nawaz Sharif has developed ‘blockage’ in one of his heart arteries and that the medical treatment may take a little more. It was not clear at this time that how much time would be required for the prime minister to completely recover and be able to return to the country. However, the sources said that for the time being the prime minister’s stay in London has been extended owing to medical treatment. Prime Minister Nawaz Sharif Wednesday left for London for medical check-up which he, according to his spokesperson, had been putting off for a while due to official responsibilities.