ISTANBUL--Turks are set to approve a package of constitutional amendments that will hand Prime Minister Recep Tayyip Erdogan and his government more control over the courts and military. The changes were backed by 60 per cent of voters to 40 per cent against, with 70 per cent of votes counted, NTV television reported. The margin is larger than any foreseen by pre-vote surveys. Erdogan's own polls predicted the measures would pass with 55 per cent support. Voting ended in the referendum, regarded as a test of support for Erdogan's Islamist-rooted AK Party, and results were expected later on Sunday. The referendum was widely viewed as a preview of Erdogan's chances of winning a third term in office at general elections to be held by July. The ‘yes' vote will bolster a government that has presided over record economic growth even as critics accuse it of seeking to undermine Turkey's secular system. Generals and judges who see themselves as the last line of defence against encroaching Islamism have frequently clashed with the prime minister since his party came to power in 2002. Coup anniversary A strong win means "there won't be a surprise at the elections" and is likely to be welcomed by investors, Hakan Kalkan, who helps manage $700 million in assets at Autonomy Capital in London, said in an interview before the vote. Opposition politicians campaigned against the measures, saying they undermine the separation of powers and would hand Erdogan too much power. The leader of the main opposition Republic People's Party, Kemal Kilicdaroglu, was unable to vote in Istanbul after failing to register a change of address. Voting day marked the 30th anniversary of a 1980 coup that brought Turkey three years of army rule and a new constitution written by the military dictatorship. Generals imprisoned thousands of Kurds, Marxists and extreme nationalists in a bid to halt political killings that were destabilising the country. Before yesterday's vote, analysts said nationalist and Kurdish voters held the key to an Erdogan victory. The package allows members of the armed forces to be tried in civilian rather than military courts for crimes against the state. The 15th article of the constitution is abolished, allowing the architects of the 1980 coup, including its leader, General Kenan Evren, now in his nineties, to be put on trial. The amendments also restructure Turkey's judiciary, giving the government more control over appointments to the Supreme Board of Prosecutors and Judges and the Constitutional Court. The Constitutional Court, which has frequently clashed with Erdogan and struck down measures passed by his lawmakers, will be expanded to 19 members from 11, with 16 appointed by the president and the other three by parliament. Critics including the opposition Republic People's Party and Nationalist Action Party say the amendments allow Erdogan to enact what they say is his hidden Islamist agenda. Erdogan says they bring Turkey further in line with democratic standards of the European Union, which Turkey is in talks to join. Other amendments allow for "positive discrimination" in favour of women, children, the elderly and disabled, and expand the rights of workers to form and join unions. Turkey's main opposition leader was unable to vote in a referendum on whether to amend the constitution due to a mix-up over where he could cast his ballot.