MOSCOW — Russian television reported on Monday that the Ukrainian and Russian intelligence services had worked together over many weeks to thwart an assassination attempt on the Russian prime minister, Vladimir V. Putin.

The report came less than a week before the Russian presidential election on Sunday, raising questions about the timing, in part because two suspects were arrested weeks ago. Mr. Putin, the dominant figure in Russian politics, is widely expected to return to the presidency, which he held for two terms before becoming prime minister in 2008.

The report by the government-controlled broadcaster, Channel One, said the two suspects were arrested in the Ukrainian city of Odessa after surviving an explosion in an apartment there on Jan. 4. A third man died in the blast, which occurred while the men were mixing chemicals for an explosive device, according to the report. The authorities said the Chechen militant leader Doku Umarov had sent the three men to the city, Channel One reported.

One suspect, Ilya Pyanzin, was arrested immediately after the explosion and the second, Adam Osmayev, a month later, according to the report.