By Ozan Ergenay and Andrey Sychev

(Reuters) - Volkswagen shares were down 3% in early trade on Monday with analysts citing uncertainty about the automaker's cost-cutting deal with unions and likely headwinds in 2025.

Friday's agreement, hailed by unions as a "Christmas miracle", calls for more than 35,000 future job cuts and a reduction of production by almost a quarter, but without immediate plant closures or layoffs.

It fell short of management's initial ambitions and market expectations, and lacked a sense of urgency, according to Jefferies analyst Philippe Houchois.

Given the pace of change at rival firms and the competitive environment in the sector, "there is a risk that the gains will come too late and will not be sufficient," ODDO BHF analysts wrote in a note to clients.

VW's earnings momentum is also unlikely to improve significantly next year given weak demand in China and potential tariffs after Donald Trump's election, they added.

Analysts at both Jefferies and ODDO BHF said more details were needed to understand how VW's management intends to achieve its announced cost cuts of 15 billion euros ($15.61 billion) a year.

The deal's impact on costs will become visible only after 2025, and this is just the beginning of a 5-year process, J.P. Morgan analysts wrote in a note, though they called it "a positive step in the right direction".

Volkswagen shares were down 2.39% at 86.68 euros in Frankfurt as of 1051 GMT.

Shares in German peers BMW, Mercedes-Benz, VW's major shareholder Porsche Automobil Holding and Porsche AG were down between 0.9% and 1.7%.

Volkswagen shares are down more than 20% this year and are trading around their 2010 levels.

($1 = 0.9610 euros)