BAGHDAD, Iraq – Authorities insisted yesterday that they won’t give in to terrorists’ demands to free female Iraqi prisoners despite the plea of a tearful British hostage begging Britain to save his life in a video released by his captors.

Meanwhile, Iraq’s most powerful Shiite cleric, Ayatollah Ali al-Sistani, said that increasing violence must not be used as a pretext for delaying elections scheduled for late January.

Ayatollah al-Sistani “stresses the necessity of holding elections on time and the necessity of preparing the atmosphere…under international supervision to be credible and transparent,” Hamed al-Khafaf, an aide to the ayatollah, said yesterday in a telephone interview from Beirut.

Iraq’s Shiite majority is eager to hold elections since they expect to dominate whatever government emerges. U.N. Secretary-General Annan, however, has questioned whether elections can take place if violence does not ease.

Violence has intensified in recent weeks – with insurgents setting off near-daily car bombs. For a second day, American forces battled Shiite militiamen in the Baghdad slum of Sadr City, with American warplanes firing on insurgents. An explosion went off yesterday evening in Baghdad, though its cause was not immediately known. The military announced that an American Marine was killed.

The fighting and rash of kidnappings have shown the vulnerability even in the capital, where British hostage Kenneth Bigley and two American colleagues were abducted from their home last week. The two Americans were beheaded, and their bodies dumped not far from their Baghdad residence.

In a video made public Wednesday, Mr. Bigley appealed to Prime Minister Blair to intervene and meet his kidnappers’ demands. “I think this is possibly my last chance,” he said. “I don’t want to die.” Mr. Bigley’s brother, Paul, accused America of wrecking efforts to save his brother’s life after American officials and Mr. Allawi quickly quashed a comment by an Iraqi official that one of the female prisoners would be freed yesterday.

In another hostage drama, two statements surfaced on the Internet from different groups, each claiming to have killed two kidnapped Italian aid workers. The second statement said a video of the slaying of the two women, Simona Pari and Simona Torretta, would be made public, but Italy cast doubt on both claims’ authenticity.