WASHINGTON — PARIS — European Union sanctions against Iran could be eased as soon as December, officials said Monday, after a potentially history-shaping deal that gives Tehran six months to increase access to its nuclear sites in exchange for keeping the core components of its uranium program.

The deal, announced Sunday, envisages lifting some of the sanctions that have been crippling the country’s economy. The sanctions were in response to fears that Tehran is using its nuclear program to build atomic arms. Iran denies it wants such weapons.

“A Europe-wide decision is necessary” to ease EU sanctions French Foreign Minister Laurent Fabius told Europe 1 radio. “That’s expected in several weeks, for a partial lifting that is targeted, reversible.”

“It could be in December, it could be in January, it depends on how long the legislative process takes,” EU foreign affairs spokesman Michael Mann told reporters in Brussels.

The United States and the European Union have separate sanctions on Iran. Easing the European restrictions would affect numerous areas including trade in petrochemicals, gold and other precious metals, financial transfers to purchase food and medicine, and the ability of third countries to use EU-based firms to insure shipments of Iranian oil again.

Mann said work on amending the EU regulations was already beginning, but cautioned that changes depend on the Iranian government living up to its end of the deal.

“It’s important that both sides of the bargain are implementing this agreement, so we would coordinate timing-wise also with the Iranian side,” the EU spokesman said.

The deal reached Sunday will allow Iran to keep the central elements of its uranium program while stopping its enrichment at a level lower than what is needed for nuclear arms. In addition to a six-month window for Iran to allow more U.N. access to nuclear sites, sanctions will be eased — notably in the oil, automotive and aviation industries — though not ended.

The agreement is a first step — one that Israel has condemned as a “historic mistake” that effectively accepts Iran as a threshold nuclear weapons state. Israel has found common cause with Saudi Arabia, which shares concerns about a nuclear-armed Iran and Tehran’s growing regional influence.