ISTANBUL: Turkey's lira slipped against the dollar on Tuesday as investors remained uneasy about President Tayyip Erdogan's influence on economic policy after his call for the main opposition party's role in the country's biggest lender to be investigated.

The lira stood at 6.3800 to the dollar at 0628 GMT, weakening from a close of 6.3150 on Monday. The declines this week have erased most of the gains made after last Thursday's 6.25 percentage point central bank rate hike.

One analyst, who declined to be named, said sentiment was hit by Erdogan's comments in Monday's Hurriyet newspaper saying authorities should look into members of the main opposition  Republican People's Party (CHP) over its 28 percent stake in Isbank.

Those comments triggered declines Isbank shares and the Istanbul bourse banking index.

"At the same time, there is continued foreign currency demand from locals," the analyst said, adding that there was a wait-and-see mood in the market ahead of Thursday's announcement of the government's medium-term economic programme.

"If (the lira) remains above this level, it will create the perception that the central bank rate hike was ineffective and this may lead to a further worsening," the analyst added.

Since gaining expanded executive powers in July, the president has tightened his grip on the economy and monetary policy, appointing his son-in-law, Berat Albayrak, as finance minister and taking charge of the sovereign wealth fund.

The lira has weakened 40 percent against the U.S. currency this year on concerns about growing authoritarianism and a lack of central bank independence. A diplomatic spat with the United States has added to pressure on the Turkish currency.