Hungarian Prime Minister Ferenc Gyurcsany said on Monday companies in his country were eyeing investments in various Indonesian infrastructure projects, which an Indonesian official said could be worth up to $4 billion.

Indonesia, the world's fourth most populous nation, has been struggling to attract foreign investment since the Asian economic crisis of the late 1990s.

"On investments, we are reviewing possibilities for investing in mining sectors, infrastructure and energy," the prime minister said through a translator at a news conference in Jakarta.

Hungary's economic and transport minister Janos Koka said "a memorandum of understanding was signed between the governor of South Sumatra and the representatives of Hungarian companies".

"They are interested in putting together the projects, focusing on coal mining, railway reconstruction and energy," Koka added.

Sjahrial Oesman, the governor of Indonesia's South Sumatra province, said that from looking at the projects the total amount could reach $4 billion, and expected more detailed discussions could come by September.

The Hungarian prime minister was on a four-day state visit to Indonesia that began on July 23.