PM Office shows Imran Khan boards into a special plane prior to his departure to Moscow at the military airbase Islamabad on Wednesday. AFP

Pakistani Prime Minister Imran Khan left for Moscow on Wednesday to push for the construction of a long-delayed, multi-billion-dollar gas pipeline to be built in collaboration with Russian companies, an official said.

Imran's trip to meet President Vladimir Putin and discuss issues including economic cooperation comes hours after a number of Western nations hit Russia with new sanctions for its military deployment into parts of eastern Ukraine.

Imran is the first Pakistani prime minister to undertake a bilateral visit to Moscow in 23 years. The visit is part of efforts by the two sides spanning over a decade to bury their cold-war rivalry and enter into a new era of cooperation.

"Both countries are eager to launch the project at the earliest," Pakistan's energy ministry spokesman told Reuters about the Pakistan Stream gas pipeline. He confirmed that Energy Minister Hammad Azhar is accompanying Imran on the visit.

The 1,100km-long pipeline, also known as the North-South gas pipeline, was initially agreed to in 2015 and was to be financed by both Moscow and Islamabad, using a Russian company to construct it.

It is unclear how the latest sanctions will affect the project, which would deliver imported Liquified Natural Gas (LNG) from Karachi on the Arabian Sea coast to power plants in the northeastern province of Punjab.

The project is important for Pakistan — particularly the power sector — as the country's dependence on imported LNG grows in the face of dwindling indigenous gas supplies.

The pipeline project has already suffered delays because of earlier sanctions.

"This North-South pipeline suffered, one of the reasons...was the companies we were negotiating with, turned out that US had applied sanctions on them," Imran told Russia Today on Tuesday.

"So, the problem was to get a company that wasn’t sanctioned," he said of the project.

Russia and Pakistan were in opposite camps during the "Afghan Jihad" though now both have convergence on the way forward for Afghanistan.

The visit, however, is likely to be overshadowed by the brewing conflict between Russia and Ukraine that pitted Moscow against the West.

"There is no doubt that the West will closely follow our prime minister’s visit. Every word and statement he makes in Moscow will be scrutinised. That’s where we need deft diplomacy,” commented a senior diplomat and cautioned that any misstep could have serious backlash for the country.

The debate raged in Pakistan with some questioning the timing of the visit. But the officials said the visit was planned well in advance before the current crisis. Therefore, it was not wise to postpone or cancel the trip at the last minute.

Nevertheless, the government was advised to tread carefully and was told not to take any steps that may give the impression that Pakistan is taking sides in the highly fluid situation.

Ahead of the prime minister’s visit, the Ukrainian ambassador to Islamabad sought Pakistan’s help to defuse the tension between Moscow and Kyiv. The Ukrainian envoy requested Pakistan’s assistance in case Russia invades Ukraine.

While the relationship between Pakistan and Russia has seen improvement in recent years, Islamabad also has longstanding ties particularly in the defence field with Kyiv.

In what appears to be a balancing act, Pakistan’s ambassador to Kyiv Major General Noel Israel Khokar met Ukrainian first deputy Minister of Foreign Affairs Emine Dzheppar on Monday. The Ukrainian deputy foreign minister in a tweet said Pakistani envoy expressed support for the "sovergnity and territorial integrity” of Ukraine.

Mindful of the sensitivities involved, Imran told Russian-state owned television network RT on Tuesday that Pakistan hoped for a "peaceful solution” to the ongoing conflict between Russia and Ukraine.

"I am not a believer in military conflicts. I believe the civilised societies resolve the difference through dialogues and countries that rely on military conflicts have not studied history properly," Khan told Russian TV ahead of his departure to Moscow.

He said he was sure that people in Ukraine and Russia were aware of the consequences of an impending conflict. Outlining Pakistan’s policy, the prime minister made it clear that Islamabad was opposed to "bloc politics” as it suffered in the past because of this approach.