The grandson of Ayatollah Ruhollah Khomeini, founder of Iran's Islamic Republic, will not be allowed to stand in this month's election in Iran, the clerical vetting body said on Wednesday, in a blow to reformist forces in the country.

Hassan Khomeini, 43, the first member of the Khomeini family to register for polls and an ally of President Hassan Rouhani, lost an appeal to the body against a ban. The setback comes at a time of growing rivalry between reformists and conservatives stirred by a deal with world powers that lifted economic sanctions against Tehran as part of a nuclear agreement.

Hardliners fear Iranian voters will now be more inclined to reward reformist and moderate candidates in Feb. 26 elections to the 290-seat parliament and the 88-seat Assembly of Experts, the body responsible for choosing the next Supreme Leader.

The Guardian Council, a clerical vetting body responsible for overseeing all elections, excluded thousands of parliamentary hopefuls and hundreds of candidates for the Assembly of Experts, leaving a field mostly of conservatives.

Under pressure from the government, the Council overturned hundreds of bans on parliamentary candidates last week, rekindling the hopes of reformists and moderates.

But the final list of candidates for the Assembly of Experts, published on Wednesday, makes it clear that the Guardian Council intends to keep reformists and moderates away from this crucial clerical body.

Ayatollah Khomeini led a revolution that saw the overthrow of the Shah in 1979 and creation of an Islamic Republic. Hardliners say they are the guardians of his legacy while his grandson feels his views mirror his grandfather's values.

The Council said that Hassan Khomeini "has not enough Islamic knowledge to distinguish the next Supreme Leader," a family member was quoted by the ISNA news agency as saying.

Ayatollah Khamenei is 76, so the new assembly is expected to play a significant role in choosing his successor since its members are only elected every eight years.

Reformist and moderate candidates have accused the Guardian Council of eliminating rivals.

"The Guardian Council is now more than ever under pressure by the Islamic Republic's sworn enemies," the Council said in a statement published on its website on Tuesday.

"The Council would stand firm to protect people's rights and the Islamic Republic's values."