of power in the representative European institutions. Upon joining the EU, Turkey's 83 million inhabitants would bestow it a large number of MEPs in the European Parliament. This is because the European Parliament distributes seats to member nations according to their population. Therefore, if Turkey is admitted, it could influence the EU legislation and administration in line with its own policies. If Turkey were to join the European Union, Istanbul would become the most populous metropolis in the EU (as of 2004). Foreign relations with EU member states Cyprus Cyprus was divided when, on 20 July 1974, Turkey invaded and occupied a third of the island in response to an Athens-engineered coup aimed at annexing Cyprus to Greece. Since then, Turkey has refused to acknowledge the Republic of Cyprus (an EU member since 2004) as the sole authority on the island, and recognizes the self-declared Turkish Republic of Northern Cyprus since its establishment in 1983. The Turkish invasion in 1974 and the resulting movement of refugees along both sides of the Green Line, and the establishment of the self-declared Turkish Republic of Northern Cyprus in 1983, form the core issues which surround the ongoing Cyprus dispute. Turkey and the Turkish Cypriots backed the 2004 Annan Plan for Cyprus aimed at the reunification of the island, but the plan was subsequently rejected by Greek Cypriots on the grounds that it did not meet their needs. According to Greek Cypriots, the latest proposal included maintained residence rights for the many Anatolian Turks who moved to Cyprus after the invasion (and their descendants who were born on the island after 1974), while the Greek Cypriots who lost their property after the Turkish invasion would be granted only a restricted right of return to the north following the island's proposed reunification. Although the outcome received much criticism in the EU as well, the Republic of Cyprus was admitted into the EU a week after the referendum. The Turkish government has refused to officially recognise the Republic of Cyprus until the removal of the political and economic blockade on the Turkish Republic of Northern Cyprus. Turkey's non-recognition of the Republic of Cyprus has led to complications within the Customs Union. Under the customs agreements which Turkey had already signed as a precondition to start EU membership negotiations in 2005, it is obliged to open its ports to Cypriot planes and vessels, but Turkey has not