TEHRAN (Reuters) – Iran has arrested four Iranians accused of involvement in a U.S.-financed plot aimed at toppling its Islamic system of government, the judiciary said Tuesday.

The announcement came a week before the inauguration of Barack Obama as U.S. president. In a shift from George W. Bush’s approach, he has pledged to increase diplomatic efforts to engage Iran and talk directly to its leaders.

The two countries, which have not had diplomatic relations for three decades, are embroiled in a long-running row over Iran’s disputed nuclear work, which Washington says is aimed at making bombs. Tehran denies the charge.

Iranian officials often accuse their Western foes of seeking to undermine the Islamic state through a “soft” or “velvet revolution” with the help of intellectuals and others inside the country.

Judiciary spokesman Alireza Jamshidi said the accused were arrested in Tehran and their verdicts would be announced soon.

“The news whose details which will be announced either tomorrow or the day after is in connection to a soft network whose intent was to topple (the Islamic system), with U.S. government funding,” Jamshidi told a news conference.

“One of the goals these individuals were pursuing in Iran was to set up a network to topple the Islamic establishment, all of whose operators have been arrested,” he said.