By Myles Neligan and Pascal Fletcher
LONDON/MIAMI (Reuters) - BP <:BP.LO:>s relief well is closing in to start a permanent kill of the blown-out Gulf of Mexico oil well this week, unless an approaching weather system disrupts the timing, the top U.S. oil spill response chief said on Monday.
"They are closing in on the last 30-40 feet ... It's ongoing and going in segments," retired Coast Guard Admiral Thad Allen told a conference call to update on the final stages of definitively plugging the world's worst offshore oil spill.
"We expect that sometime before the end of the week we will be able to intercept the annulus (space between the well shaft and surrounding rock) and commence the kill," Allen added.
He said the spill response authorities were closely watching a tropical weather system moving east over the Florida peninsula, which forecasters see crossing in a few days near BP's Deepwater Horizon spill site in the Gulf of Mexico.
Allen said that depending on its strength and direction this system could affect the timing of the relief well "bottom kill" operation to permanently shut down the crippled Macondo well, which was provisionally capped on July 15.
Forecasters were giving this weather disturbance a low 20 percent chance of strengthening into a tropical depression.
A cement cap installed on the top of the Macondo deepwater well last week was holding, Allen said.
In London, BP said the cost of dealing with the oil spill, which has soiled marshes, fisheries and tourist beaches along the U.S. Gulf Coast, had risen to $6.1 billion, including $319 million in compensation payments to businesses and individuals affected by the spill.
BP shares were up around 2 percent in London.
With the well sealed, U.S. President Barack Obama's administration is working to reassure Gulf Coast residents that operations to completely clean up what's left of the spilled oil and compensate those affected will not slacken off.
Gulf Coast residents and business owners from Louisiana to Florida have reacted with alarm to a report by government scientists asserting that around 75 percent of the spilled oil had either evaporated, dispersed or been contained.
They say they fear government and media attention will fade and they will be abandoned as they struggle to cope with incomes and livelihoods devastated by the pollution disaster.
(Additional reporting by Scott DiSavino in New York; Writing by Pascal Fletcher; Editing by Vicki Allen)
