Voices of concern about the possibility of a wave of postponements of high-level visits because of political instability here have been raised in Jerusalem after British Foreign Secretary David Miliband cut short a Middle East visit without meeting Israeli leaders, and Canadian Prime Minister Stephen Harper postponed his trip altogether. Miliband, who arrived Monday and held talks with Palestinian Authority officials in Ramallah, cut short his trip and returned to London early Tuesday morning without meeting Prime Minister Ehud Olmert or Foreign Minister Tzipi Livni as planned. He did, however, speak to Livni by phone. A spokeswoman at the British embassy in Tel Aviv denied that the quick return to London had anything to do with Israeli political instability, saying rather that Miliband flew back because of "important parliamentary business." Miliband was summoned back to London by British Prime Minister Gordon Brown for a key vote Wednesday on extending the detention of terrorists before they are charged from 28 to 42 days. Harper, meanwhile, was supposed to arrive on his first visit to Israel next Monday, and - according to the Canadian news agency Canadian Press - postponed his trip because of political uncertainty in Israel. One Israeli government source said that when foreign leaders detect political instability, they have a tendency to stay away because they are not sure whether anyone has the authority to make key decisions. Harper, a staunch supporter of Israel, was to make his first visit to the region, visiting Israel, the Gaza Strip and Jordan. A few days before his visit was cancelled, he gave his approval to Tel Aviv University to print up invitations for a ceremony at the university at which he was to be awarded an honorary doctorate. Foreign Ministry spokesman Aryeh Mekel said the postponement was due to "technical reasons" and scheduling problems for both Olmert and Harper. "Israel-Canada relations continue to be excellent," he said. In his nearly two-and-a-half years in office, Harper has emerged as a staunch supporter of Israel. During the Second Lebanon War, he caught a lot of domestic criticism for calling Israel's response to Hizbullah "measured," and in a radio interview just prior to Israel's 60th anniversary said that in some circles, "anti-Israeli sentiment really is just a thinly disguised veil for good old fashioned anti-Semitism, which I think is completely unacceptable. We learned in the Second World War that those who would hate and destroy the Jewish people will ultimately hate and destroy the rest of us as well, and the same holds true today." No reason for the postponement of Harper's visit was available from the Canadian embassy in Tel Aviv. There have been reports in the Canadian press, however, that the cancellation had to do with Harper's own domestic political problems, and his need to find a replacement for Maxime Bernier, who resigned as foreign minister last month.