JERUSALEM — The West Bank tomb of Yasir Arafat has been cordoned off and screened from public view ahead of an expected exhumation, a Palestinian Authority official said Tuesday, four months after a television investigation raised new suspicions that the Palestinian leader had been poisoned.

The preparatory work, involving the removal of layers of stone and concrete, is being done manually and is expected to take at least two weeks.

“It needs to be done meticulously and privately, out of respect for the late president and our religious traditions,” the official said, speaking on the condition of anonymity because she was not authorized to speak about the issue.

Tawfiq Tirawi, the chief of the Palestinian committee overseeing the inquiry, issued a statement on Monday announcing that the mausoleum was closed to visitors, without specifying a date for the exhumation.

The structure lies within the walls of the compound in Ramallah where Mr. Arafat, long the symbol of the Palestinian national struggle, was confined under an Israeli Army siege and virtual house arrest for more than two years while outside raged the second Palestinian intifada, or uprising, and the Israeli clampdown.

The preparations for the exhumation have been enveloped in almost as much mystery and contention as was the death of Mr. Arafat in 2004, at the age of 75.  

Mr. Arafat became ill in October 2004 and was flown by helicopter out of his headquarters and transferred to a French military hospital, where he died about two weeks later of unannounced causes.

The records showed that he had died of a stroke that resulted from a bleeding disorder caused by an underlying infection. The infection was never identified. The hospital found no traces of poisons.

In July, Mr. Arafat’s widow, Suha, called for an exhumation in an interview with Al Jazeera, the Arabic television channel based in Qatar, after it reported that Mr. Arafat might have been poisoned with polonium, a radioactive element associated with K.G.B.-style assassination intrigues.

With Mrs. Arafat’s help, the news channel carried out what it called an in-depth investigation into the circumstances surrounding Mr. Arafat’s death.

Mrs. Arafat gave the broadcaster a copy of Mr. Arafat’s medical records as well as personal effects, including clothing he had worn close to his death, his toothbrush and his trademark black-and-white checkered headdress. Al Jazeera said it took the items to the best laboratories in Europe for forensic testing.

At the University of Lausanne’s Institute of Radiation Physics in Switzerland, doctors found what they said were unusually high levels of a highly toxic radioactive isotope, polonium 210, in certain items but added that further testing of Mr. Arafat’s remains would be necessary before determining that he had been poisoned.

Mrs. Arafat has since requested that the French authorities open a murder inquiry, and on Sunday, Mahmoud Abbas, the Palestinian Authority president and Mr. Arafat’s successor, said Russian experts would also be helping with the investigation. French, Swiss and Russian teams are now expected in Ramallah for testing the remains later this month.