BRUSSELS - The European Commission has proposed changes to its planned embargo on Russian oil in a bid to win over reluctant states, three EU sources told Reuters on Friday.

The tweaked proposal, which EU envoys were discussing at a meeting on Friday morning, includes giving Hungary, Slovakia and the Czech Republic more time to adapt to the embargo, and help with upgrading their own oil infrastructure, the sources said.

It also includes a three-month transition before banning EU shipping services from transporting Russian oil, instead of the initial one month, one of the sources added, speaking on condition on anonymity.

Under the tweaked proposal, Hungary and Slovakia will be able to buy Russian oil from pipelines until the end of 2024, whereas the Czech Republic could continue until June 2024, if it does not get oil via a pipeline from southern Europe earlier, the sources said.

Under the original proposal, EU countries would have to stop buying Russian crude oil six months after adoption of the measure, and halt imports of refined oil products from Russia by the end of the year. Hungary and Slovakia were initially given until the end of 2023 to adapt.

Bulgaria had also asked for exemptions, but has not been offered concessions on deadlines, one official said, "because they don't have a real point". The other three countries who were granted more leeway "have an objective problem," the official added.

Hungary's Prime Minister, Viktor Orban, said earlier on Friday that Hungary would need five years and huge investments in its refineries and pipelines to be able to transform its current system which relies about 65% on Russian oil.

The proposed extension of the period to introduce a shipping ban for EU companies to transport Russian oil worldwide is meant to address concerns raised by Greece, Malta and Cyprus about the impact of the measure on their shipping companies, one official said.

Under the original proposal, presented by the Commission on Wednesday, EU companies would have had to stop offering shipping, brokerage, insurance and financing services for the transport of Russian oil worldwide in a month's time.

(Reporting by Francesco Guarascio @fraguarascio and Robin Emmott; Editing by Hugh Lawson and Andrew Heavens)