Interior Minister Muammer Guler (pictured left) and Economy Minister Zafer Caglayan (right) announced their resignations early on Wednesday, just hours after Prime Minister Recep Tayyip Erdogan returned from a trip abroad.

They were followed later in the day by Environment Minister Erdogan Bayraktar.

A total of 24 people, including the sons of both Caglayan and Guler, have been arrested as part of three separate bribery investigations centering on state-run lender Halkbank. Bayraktar's son was also detained briefly.

Caglayan and Guler portrayed the scandal as an orchestrated effort to create discord in Turkey.

"I have resigned from my post of economy minister to help the truth to come out and to foil this ugly plot, which has impacted my child and my close work colleagues among others," Caglayan said in a statement.

Guler made a separate statement, calling the affair "a dirty set-up against our government, party and country."

Turkish President Abdullah Gul had said on Tuesday that Prime Minister Erdogan was preparing a cabinet reshuffle upon his return from an official visit to Pakistan.

The prime minister held a special late-night meeting with some of his ministers, including Guler, at his Ankara home.

Lira sinks in value

Erdogan was expected to replace 10 ministers - half of his cabinet - in the run-up to local elections on March 30.

Halkbank has been a source of friction between the United States and Turkey over allegations that it was involved in facilitating illegal sanctions-breaking trade with Iran. The scandal has badly affected the Turkish economy, pushing the national currency - the Turkish lira - to record lows against the US dollar.

Erdogan, who has led Turkey for more than a decade, described the probe as a "smear campaign" against the country's national interests. He responded to the investigation by sacking dozens of high-ranking police officials.

President Gul - who is aligned with Erdogan's own Justice and Development Party (AKP) - has also condemned the investigation as "political plotting," but concedes that allegations of bribery should not be covered up. He said the investigation would be judged in independent courts.

rc / se (AFP, AP, dpa, Reuters)