The changes are only now starting to take place after the Withdrawal Agreement between the UK and EU came into effect on 1 February.
As a third country, the UK will no longer be represented at EU level, so Parliament is now composed of 705 seats instead of 751.
Of the 73 UK seats, 27 have been redistributed to Member States and the remaining 46 will be held in reserve for any future EU enlargements.
A Parliament spokesman explained the new set up, saying, “Under the new arrangements, no Member State will lose any MEPs.”
“A few countries will see an increase in their number of representatives, in line with the new relative population sizes of Member States, while the new distribution also ensures a minimum level of representation for the smallest EU countries.”
Member States that will see an increase in the number of their MEPs announced the new members at last week’s plenary in Strasbourg.
Their term officially started on 1 February and last week was their first experience of parliamentary life.
“The committees’ new composition is likely to be presented at the next plenary and then committees will meet and elect their chairs and vice-chairs where relevant” European Parliament spokesman
All 27 new MEPs were elected on pan-European lists at last May’s European elections. So far, 23 have been confirmed while the rest, from the Netherlands, are yet to be announced.
Three committees will also increase in numbers as a result of the shake-up. They are the environment committee, increasing by five to 81 members; international trade, up by two to 43 members, and the industry and research committee, rising by six to 78 MEPs.
The two British committee chairmen will be replaced: Chris Davies, former chair of the fisheries committee, and Lucy Nethsingha, who chaired the legal affairs committee.
Three UK vice-chairs will also have to be replaced. They are Seb Dance (Environment, Public Health and Food Safety), Julie Ward (Culture and Education) and Irina von Wiese (Human Rights Subcommittee).
Elsewhere, four UK coordinators will have to be replaced: Shaffaq Mohammed, Jude Kirton-Darling, von Wiese and Geoffrey van Orden, while changes are also needed to inter-parliamentary delegations.
Parliament’s political groups will only decide on the new membership of each committee and subcommittee after all 27 of the new MEPs have taken their seats.
The spokesman told this website, “We're waiting for Netherlands (3 members) to notify their post-Brexit MEPs. We are told the Dutch members will be confirmed later in February probably.”
"As a third country, the UK will no longer be represented at EU level, so Parliament is now composed of 705 seats instead of 751"
“The committees’ new composition is likely to be presented at the next plenary and then committees will meet and elect their chairs and vice-chairs where relevant.”
The spokesman said, “The redistribution of seats ensures that no EU country loses any seats, while some gain from one to five seats to address under-representation following demographic changes.”
“This principle of ‘degressive proportionality’ means that smaller countries have fewer MEPs than bigger countries, but also that MEPs from a larger country represent more people than their counterparts from smaller countries.”
With the withdrawal of the UK now effective, a new chapter of negotiations will begin in early March.
Besides trade and fisheries, issues to be discussed - and which will form part of any final agreement - range from the fight against climate change to terrorism threats, and from cooperation in research to shared defence structures.
The transition period starting on 1 February is set to expire at the end of December 2020. Any agreement on the future EU-UK relationship will have to be fully concluded before that point if it is to come into force on 1 January 2021.
The transition period can be extended once for one to two years, but the decision to do so must be taken by the EU-UK Joint Committee before 1 July and UK Prime Minister Boris Johnson says he will not extend the deadline.
The spokesman added, “Parliament will follow closely the work of the EU negotiator Michel Barnier and continue to influence the negotiations through resolutions.”
Parliament’s newly-named UK Coordination Group is led by German member David McAllister, replacing Belgian deputy Guy Verhofstadt.
“He will liaise with the EU Brexit task force and coordinate with all competent committees,” said the spokesman.