Afghanistan
Albania
Algeria
American Samoa
Andorra
Angola
Anguilla
Antigua and Barbuda
Argentina
Armenia
Aruba
Australia
Austria
Azerbaijan
Bahamas
Bahrain
Bangladesh
Barbados
Belarus
Belgium
Belize
Benin
Bermuda
Bhutan
Bolivia
Bonaire
Bosnia and Herzegovina
Botswana
Brazil
British Virgin Islands
Brunei Darussalam
Bulgaria
Burkina Faso
Burundi
Cabo Verde
Cambodia
Cameroon
Canada
Cayman Islands
Central African Republic
Chad
Chile
China PR
Chinese Taipei
Colombia
Comoros
Congo
Cook Islands
Costa Rica
Côte d’Ivoire
Crimea
Croatia
Cuba
Curaçao
Cyprus
Czechia
Denmark
Djibouti
Dominica
Dominican Republic
DR Congo
Ecuador
Egypt
El Salvador
England
Estonia
Eswatini
Ethiopia
Faroe Islands
Fiji
Finland
France
French Guiana
Gabon
Gambia
GDR
Georgia
Germany
Ghana
Gibraltar
Gozo
Greece
Greenland
Grenada
Guadeloupe
Guam
Guatemala
Guernsey
Guinea
Guinea-Bissau
Guyana
Haiti
Honduras
Hong Kong SAR
Hungary
Iceland
India
Indonesia
IR Iran
Iraq
Israel
Italy
Jamaica
Japan
Jordan
Kazakhstan
Kenya
Korea Republic
Kosovo
Kuwait
Kyrgyz Republic
Lao PDR
Latvia
Lebanon
Lesotho
Liberia
Libya
Liechtenstein
Lithuania
Luxembourg
Macau
Madagascar
Malawi
Malaysia
Maldives
Mali
Malta
Martinique
Mauritania
Mauritius
Mayotte
Mexico
Moldova
Mongolia
Montenegro
Morocco
Mozambique
Myanmar
Namibia
Nepal
Netherlands
New Caledonia
New Zealand
Nicaragua
Niger
Nigeria
North Macedonia
Northern Ireland
Northern Mariana Islands
Norway
Oman
Pakistan
Palestine
Panama
Papua New Guinea
Paraguay
Peru
Philippines
Poland
Portugal
Puerto Rico
Qatar
Republic of Ireland
Réunion
Romania
Russia
Rwanda
Saint Martin
Samoa
San Marino
São Tomé e Príncipe
Saudi Arabia
Scotland
Senegal
Serbia
Seychelles
Shetland
Sierra Leone
Singapore
Sint Maarten
Slovakia
Slovenia
Solomon Islands
Somalia
South Africa
South Sudan
Spain
Sri Lanka
St. Kitts and Nevis
St. Lucia
St. Vincent and the Grenadines
Sudan
Suriname
Sweden
Switzerland
Syria
Tahiti
Tajikistan
Tanzania
Thailand
Timor-Leste
Togo
Tonga
TR Northern Cyprus
Trinidad and Tobago
Tunisia
Türkiye
Turkmenistan
Turks and Caicos Islands
Tuvalu
Uganda
Ukraine
United Arab Emirates
United States
Uruguay
US Virgin Islands
Uzbekistan
Vanuatu
Vatican City
Venezuela
Vietnam
Wales
Yemen
Zambia
Zanzibar
Zimbabwe
That’s according to German outlet Kicker, who claims Gerardo Seoane’s side are keen to bring in the Norweigan defender, who is understood to be valued at just £12.9m (€15m).
Ajer, 23, is expected to depart Celtic once this summer’s transfer window opens.
Seemingly unwilling to extend his contract, which expires next summer, the Hoops appear to be left with no choice but to sanction a transfer.
It has been noted that despite Bayer Leverkusen’s interest, talks between clubs have yet to take place, but that could all change in the coming weeks.
Bayer Leverkusen’s pursuit of the talented centre-back could be boosted though. The Germans and Celtic clearly have a strong relationship after Seoane recently recruited ex-Hoops right-back Jeremie Frimpong.
