United Nations ? Iranian President Mahmoud Ahmadinejad canceled a trip to New York to address the U.N. Security Council before it votes today to impose further sanctions against his country for refusing to stop enriching uranium, an Iranian Foreign Ministry spokesman said.

After intense last-minute negotiations, the six world powers that drafted the resolution overcame concerns from several council members Friday and expected it to be approved unanimously when it comes to a vote, said French Ambassador Jean-Marc de La Sabliere.

“We will be united again on this important resolution,” de La Sabliere told reporters after a closed-door Security Council meeting. “We hope that Iran will reflect on this resolution and make the right choice.”

The sanctions would ban Iranian arms exports and freeze the assets of 28 additional individuals and organizations involved in Iran’s nuclear and missile programs. About a third of those are linked to the Revolutionary Guard, an elite military corps.

Alejandro Wolff, the acting U.S. Ambassador to the U.N., called the sanctions “serious measures that underscore the severity with which the council views rejection of its resolutions.” He warned that if Iran continues to defy Security Council demands “we will continue to add measures and continue to up the pressure.”

Ahmadinejad said earlier this month that he wanted to take his case for pursuing nuclear power to the Security Council himself. Earlier Friday, a council diplomat said the Iranian president would arrive in New York at 1 a.m. today.

But Iranian Foreign Ministry spokesman Mohammed Ali Hosseini told Iranian state television later in the day that the trip had been scrapped because of “America’s obstruction in issuing visas” to the Iranian delegation that was to travel to New York.

Mohammad Mir Ali Mohammadi, press secretary for Iran’s mission to the U.N., told The Associated Press that the United States did not deliver a visa to the U.S. Embassy in Bern, Switzerland, in time for Ahmadinejad to pick it up before flying to New York for today’s session.

Officials from the handful of countries with which the U.S. does not have full diplomatic relations – like Iran – have to undergo special security checks to get a visa.

In Washington, however, the State Department insisted it had approved and issued 75 visas for Ahmadinejad and his delegation, including air crew and support staff.