If people in Crimea were still wondering how much life might change following the Russian takeover of the peninsula, they now have an answer: no more McDonald's.

The fast-food chain has announced it is closing its outlets in Crimea's main cities of Simferopol, Sevastopol and Yalta, due to what a statement on the McDonald's Ukraine website referred to only as "manufacturing reasons".

While the company said work at the three outlets was merely suspended and it hoped to reopen them, staff at the restaurants would be offered the chance to relocate permanently to Ukraine. Those wishing to move would keep the same job and salary and receive relocation costs for themselves and their families, including three months' rent, the statement said.

It added: "We understand and respect each employee's decision. If they do not wish to move to another city in Ukraine we will, in accordance with Ukrainian law, offer options to end their employment with a redundancy payment."

A separate statement from the McDonald's European headquarters said the closure was strictly a business decision due to "the suspension of necessary financial and banking services" and had "nothing to do with politics". It added: "We are taking numerous steps to support our employees during this time. We hope to reopen our restaurants soon so we can welcome back our loyal customers."

Russia formally annexed Crimea last month following a hastily arranged referendum in the region which was dismissed by the US, UK and other countries as meaningless. Russian troops entered Crimea after Ukraine's president, Viktor Yanukovych, was overthrown following popular demonstrations.

In another small but symbolically significant change under Russian control – though again with major implications for those directly affected – hundreds of Crimean heroin addicts issued with methadone have been told the replacement drug will no longer be made available to them.

Around 800 drug users in Crimea were issued with daily doses of methadone, but the Russian authorities said too much of it ended up on the black market and had stopped supplies. The worry is that the move could see more drug users resort to sharing needles, increasing HIV rates that had dropped in 2012, in part due to the methadone programme.

The Associated Press spoke to one methadone user in Sevastopol, Sergei Kislov, who voted for the region to join Russia but now faces losing his supply of the drug along with the others on the programme. "It is happening at such a pace that it's going to be a massacre here," he said. "They're abandoning 130 people and forcing them to fend for themselves, even if that means we'll end up stealing again and going to jail."