Turkish President Abdullah Gul is urging his country to respect the rule of law, at a time when a corruption scandal has called into question the independence of the judiciary.
In a statement marking the new year, Mr Gul said 2013 had been "a tough year for both our country and the world".
Claiming that his government is the target of a conspiracy, Mr Erdogan has removed police chiefs and judicial officials. He has alleged that followers of an Islamic movement led by US-based cleric Fethullah Gulen have infiltrated the judiciary and that the police and are using their powers to attack the government.
Mr Erdogan also tried to change police regulations to prevent further inquiries, but that move was blocked by a high court.
"Democracy is a regime of rules and institutions which is based upon the separation of powers," Mr Gul warned. "It is our common responsibility to avoid behaviours that could harm the understanding and perception of an independent and impartial judiciary."
His statement also noted progress that Turkey has made in democratic reforms and economic development under the current government.
Mr Gul has been a close ally of Mr Erdogan, but also a potential rival. Though he helped found Erdogan's Islamic-based Justice and Development Party, Mr Gul has appeared to distance himself from the prime minister by taking a more moderate tone during the scandal and during the anti-government protests that rocked Turkey in June.
Mr Erdogan is widely expected to run for president in August's elections, though neither he nor Mr Gul has declared his political intentions. Mr Gul, who enjoys wider approval ratings than Mr Erdogan, could seek to become prime minister in general elections to be held by 2015 or could take on Mr Erdogan in the presidential poll.