Paksas has vowed to run again for the presidency

The Liberal Democrat Party chose Mr Paksas as its candidate for the 13 June election at the weekend and his name was given to the election commission.

However, commission chief Zenonas Vaigauskas referred the issue to the future EU state's ethics commission.

Mr Paksas has accused his political foes of waging a "vendetta".

On 6 April he became the first European president to be impeached when parliament ruled that he had abused his powers to aid a Russian political backer and influence the outcome of an unrelated privatisation.

Denying the charges against him, Mr Paksas, a flamboyant 47-year-old former sportsman, vowed to stand again for election in accordance with the Lithuanian constitution.

At the 2003 election, he won a shock victory over the incumbent, Valdas Adamkus.

'Certain problems'

The head of the Central Electoral Commission "acknowledged that Paksas's registration might pose certain problems", Lithuanian TV reported on Monday.

Mr Vaigauskas quoted the head of the chief civil servants' ethics commission as saying that Mr Paksas had no right to stand for re-election as he had "violated the law on public and private interests in civil service".

He was therefore asking for an official ruling from the ethics commission.

Lithuanian TV noted that the election commission had to make its decision within three days.

A BBC correspondent in the region says that Mr Paksas still enjoys popular support, mainly among those who are missing out on Lithuania's economic growth ahead of the former Soviet state's entry into the EU on 1 May.