ZURICH Jan 23 (Reuters) - Requests for asylum in Switzerland plunged by nearly a third to around 27,200 last year after authorities closed the Balkan land route used by thousands to flee hot spots in the Middle East, Asia and Africa, the SEM migration agency said on Monday.

It forecast around 24,500 people would seek asylum this year but cautioned this could rise to 32,000 depending on the flow of refugees via the Mediterranean and whether a deal Europe struck with Turkey to hold back migrants held up.

In December alone, requests for asylum fell 64 percent from a year earlier, bringing the full-year drop to 31 percent after the Balkan route was interrupted in March and Swiss authorities took a tough line on the border with Italy last summer.

Neutral and landlocked Switzerland got just a fraction of the roughly 1.3 million requests for asylum across Europe last year as countries continued to process the wave of people that arrived in 2015, SEM said in a statement.

People from Eritrea made the most Swiss asylum requests last year, followed by citizens of Afghanistan, Syria, Somalia, Sri Lanka and Iraq.

Of the nearly 31,300 requests processed last year, almost 23 percent were granted asylum, SEM said. The ratio of people receiving protection was nearly 49 percent including those given provisional permission to stay in Switzerland temporarily.

Switzerland took in 621 people last year under a U.N. refugee agency resettlement programme launched in 2015, and 368 people under a European relocation scheme for refugees who had registered in Greece or Italy. (Reporting by Michael Shields; Editing by Toby Chopra)