Greece's merchant marine minister resigned Friday after spending days defending himself against accusations of unethical business deals that have deeply embarrassed the conservative government.

George Voulgarakis said in his resignation letter to the prime minister that he was quitting because he could not allow what he called politically motivated attacks against him to harm the government.

Prime Minister Costas Karamanlis accepted the resignation and appointed a former justice minister, Anastasios Papaligouras, as his replacement, government spokesman Theodoros Roussopoulos said.

Voulgarakis had been accused of setting up an offshore real estate company with his wife and using it to avoid property tax. Voulgarakis has acknowledged having the company but has insisted he did nothing illegal.

He has also been implicated in a scandal in which Vatopedi, one of the main monasteries in the autonomous monastic community of Mount Athos in northern Greece, traded low value plots of land for state-owned prime real estate. His wife allegedly was the public notary who handled part of the transaction.

Greece's Supreme Court prosecutor has ordered an investigation into the property trade between the state and Vatopedi — a monastery often visited by Britain's Prince Charles.

In his resignation letter, Voulgarakis accused the opposition socialist party of orchestrating a mudslinging campaign against him.

"Recently there has been an attempt to damage the ... government's credibility and to impose conditions of political turmoil on the country," he said in the letter released by Karamanlis' office. "With a storm of lies and mudslinging ... there is an attempt at the cold-blooded murder of my political being."

The accusations against Voulgarakis were the latest in a series of scandals to have hit the government, which holds just 152 of Parliament's 300 seats and has seen its popularity slide since winning re-election last year.

Media reports had suggested leading conservative party officials had been agitating for Voulgarakis to resign in an attempt to deflect criticism on the government.

"Go, so we can be saved" headlined the daily Eleftherotypia Friday beside a photo of Voulgarakis.