has praised Ukrainian scientists creating the country's first long-range missile. He said: "We're happy with the results of Long Neptune." It comes as Russian leader Vladimir Putin has signalled he would be interested in a partial ceasefire which would prohibit the targeting of energy installation and infrastructure - an area where Ukraine has proved particularly effective.

Kyiv has used Neptune missiles successfully since it was invaded by Russian forces three years ago. The short-range variant, based on the old Soviet-designed Kh-35 anti-ship missile, was credited with sinking Russia's Black Sea flagship, the cruiser Moskva, two months after Vladimir Putin launched his full-scale invasion in February 2022. But with a range of just 190 miles, its use was limited to shorter, tactical strikes.

The so-called "Long Neptune" is a different beast, its 600-mile range allowing Kyiv to strike deep into .

Its maiden launch on Friday successfully targeted an oil refinery in Tuapse, in 's Krasnodarskiy Kray region, exploding tank containing 20,000 tonnes of gasoline.

Such was the ferocity of the blaze that it took Russian firefighters three days to extinguish.

"A new Ukrainian missile, precise strike. The range is a thousand kilometres. Thank you to our Ukrainian developers, manufacturers and military. We continue to work to guarantee Ukrainian security," said the Ukrainian president in a statement on the Telegram social media platform following the strike.

With Russian troops enjoying momentum on the ground against , Putin has no incentive to curb his war machine and believes a complete 30-day truce would only benefit .

Likewise, however, Zelensky has little incentive to accept Putin's terms of ceasing attacks on infrastructure and energy installations.

"In essence, Putin has quietly confirmed to Trump how much our deep strikes are hurting the Russian energy sector. This is our trump card," Ukrainian MP Roman Lozinskyi said on Tuesday.

Though warmer weather means that the effects of targeting oil and gas depots will be less felt by Russians themselves, energy exports are still crucial to keeping Moscow's economy afloat.

Due to sanctions, Russia's main customer is now China, which has paid almost £200 billion in Russian imports of oil, natural gas, and coal since the war began.

Ukraine's successful strikes against Russian energy infrastructure are said to have reduced this by an astonishing 10%.

And Long Neptune is just one of around 100 missile development plans which Ukrainian scientists are currently developing, alone or in conjucntion with Romania.

These include the turbojet-propelled Peklo missile-drone with a slightly shorter 400-mile range.

US talks on Ukraine are due to continue on Monday in Jeddah, Saudi Arabia.