(Reuters) -The Ukrainian government submitted to parliament on Tuesday an amended version of its bill to tighten army mobilisation rules to ensure the country has a sufficient fighting force to pursue its campaign against Russia's invasion.

The highly sensitive reforms were sent back for revision earlier this month after a draft sparked public outcry. Lawmakers and analysts said some provisions violated the constitution and carried corruption risks.

The reforms are seen as vital because Kyiv needs to replenish its battlefield manpower. As the war nears the two-year mark, there are no longer queues of Ukrainian men at draft offices volunteering to join the fight.

A key provision in the legislation is a lowering to 25 from 27 the minimum age for the draft.

The new bill maintains key provisions of the initial draft, including the introduction of electronic call-ups and harsh punishments for people who flout mobilization rules.

It saves provisions from the earlier version to apply to Ukrainians living abroad, as citizens applying for passports would have to present their military registration documents.

The updated draft keeps a provision on serving mobilisation notices electronically into a conscript's "personal profile" which citizens are obliged to register.

Any attempt to avoid the draft will trigger potential measures by the courts, on request from military recruitment offices, including freezing of bank accounts and assets, restrictions on travel and on use of a vehicle.

Mobilisation terms are to be limited to 36 months and there will be exemptions for potential conscripts in higher education or specialised fields.

Under a new provision, certain individuals convicted of crimes will be allowed to serve in the military.

Ukraine introduced martial law when Russia launched its full-scale invasion in February 2022. Military-age men can only leave the country if they have special dispensation.

Late last year, President Volodymyr Zelenskiy said the military had proposed mobilising 450,000-500,000 more people into the army in what would represent a major undertaking.

Army Chief Valeriy Zaluzhnyi has said the figure takes into account military plans and projections of possible losses. Military analysts say the figure would cover the whole year.

(Reporting by Yuliia Dysa; Editing by Tom Balmforth, Ron Popeski and Stephen Coates)