By Duncan Mackay

Sergey Bubka is widely expected to be Sebastian Coe's main challenger to replace Lamine Diack as President of the IAAF ©Getty ImagesSergey Bubka has used Twitter to reveal that he will announce his plans for the International Association of Athletics Federations (IAAF) Presidency "in due time". 

It follows the official announcement last week by Sebastian Coe that he will stand to replace Lamine Diack when he steps down next August after 16 years as head of the world governing body.

Bubka, the world record holder for the pole vault and 1988 Olympic gold medallist, is widely seen as the Briton's main challenger. 

"Congratulations to my friend @sebcoe on his announcement. Colleagues and Friends within the @iaaforg family know about my plans," the Ukrainian wrote on his Twitter page.

He added: "Will make them public in due time".

Coe is due to launch his manifesto at a special event in London tomorrow. 

Sergey Bubka has used Twitter to congratulate Sebastian Coe and eveal he will announce his plans for the IAAF Presidency "in due course" ©TwitterSergey Bubka has used Twitter to congratulate Sebastian Coe and eveal he will announce his plans for the IAAF Presidency "in due course" ©Twitter

For many years the 50-year-old Bubka was seen as the natural heir apparent to Diack but has slipped behind Coe in recent years.

Many believe the turning point was the success of the athletics programme at London 2012, an event overseen by Coe, who was the chairman.

Bubka's decision last year to stand to replace Jacques Rogge as President of the International Olympic Committee was also considered a tactical mistake. 

Both Bubka and Coe are already travelling widely to try to drum up support for their campaigns. 

Bubka has recently visited Cali, the Colombian city due to host the IAAF World Youth Championships next year.

Coe, meanwhile, has visited Romania and Turkmenistan. 

The IAAF is due to elect a successor to Diack on the eve of next year's World Championships during its Congress at the China National Convention Centre in Beijing on August 18 to 20, where all 213 National Federations will have a vote.

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