New York (AFP) - US and Israeli authorities have arrested four men in two separate fraud schemes and who are said to be linked to last year's massive hack of computers at JPMorgan Chase, police and media reports said Wednesday.

The court documents in each of the cases, one an Israel-based ring running a pump and dump scheme for US-traded penny stocks, and the other an illicit US Bitcoin transfer operation, did not tie them to the theft of confidential details on millions of clients at the giant US bank.

But The New York Times, citing people briefed on the matter, said the four, and another man still at large, were involved in the hacking attack on the bank.

In October, JPMorgan disclosed that hackers had accessed information such as names and addresses for 76 million household customers and seven million businesses in the preceding months.

The court documents in the stock scam say Joshua Samuel Aaron, Gery Shalon, and Ziv Orenstein gained millions of dollars in their operations to artificially pump up the prices of small stocks and cash in while other investors lost heavily.

Shalon and Orenstein have been detained in Israel and placed in remand for 20 days, with US authorities having indicated they will request their extradition, an Israeli police spokeswoman said.

Aaron remains at large and is believed to be in Russia.

In the other case, Anthony Murgio and Yuri Lebedev allegedly used a front company and a licensed credit union to hide an operation to transfer large sums of money using the crypto-currency Bitcoin.

They were arrested in the United States.

Officials said the operation amounted to an illegal money transfer service, and also linked it to operations in which hackers took over people's computers and extorted ransom from them to free up their data.

The operation involved using bank accounts in Cyprus, Hong Kong and Eastern Europe, according to court filings.