Pamboukis, who was in charge of shipping — one of the main pillars of Greece’s 230 billion-euro economy — said in a letter he quit after failing to persuade Papandreou to create a separate ministry for shipping.

“For two months I have tried to re-establish a sector vital to the nation,” Pamboukis said in his letter. “My decision to resign is irrevocable.”

The government spokesman said Papandreou had accepted his resignation. Analysts said it showed a lack of unity in the government, which could hinder its effort to pull itself out of the crisis.

“It is the first sign that the government is not united,” said a political analyst who declined to be named. “It shows there is no internal balance.”

After coming to power in October 2009, the socialists abolished the ministry of shipping, angering shipowners. A year later, the government relaunched it and finally scrapped it again in a reshuffle in June. Shipping accounts for about 7 percent of GDP.

Pamboukis has also handled the investment portfolio, including a multi-billion-euro real estate development project at the old Athens airport of Hellenikon, a key EU/IMF demand in exchange for a bailout. Hopes that Qatar would invest in the project have yet to materialize.