Ukrainian President Leonid Kuchma greets the Pope

In his sermon, the Pope said both churches should try to restore the harmony than existed before the schism of 1054.

He called for work to "help restore that situation of communion in which diversity of traditions poses no obstacle to unity in faith and church life."

Despite the snub, the BBC's David Willey says the Pope is unlikely to take such a rejection as final.

Second mass

On Monday, the Pope will celebrate mass again at the same site, according to the Eastern rite.

The Pope stressed the shared history of the Catholic and Orthodox churches

Bad weather, heavy security and difficult travel conditions meant that Sunday's crowd was smaller than the 200,000 expected.

According to a spokesman for Ukrainian Catholic Churches, about 40,000 attended the mass at the Chaika airfield on the outskirts of the Ukrainian capital.

Before the service, the 81-year-old Pope drove slowly through the crowd in his bullet proof popemobile.

Worshippers had to walk five kilometres (three miles) through steady rain to reach the site.

"This is the biggest and happiest moment of my life and, only several years ago, I wouldn't have believed it possible I could come and see this greatest of men," said Andrei Letunovsky from Rostov-on-Don.

Apology

The Pope paid tribute to Christians who suffered or killed for their faith during the Soviet period, saying "the land of Ukraine is drenched with blood of martyrs".

The visit has split Ukraine's religious population

The Pope will beatify 27 Soviet-era martyrs at a ceremony in the western city of Lviv, later in his visit.

The Pope has asked the Orthodox Church to forgive past wrongs committed against them by Catholics.

"Bowing before one Lord, let us recognise our faults," he said, almost as soon as his plane touched down in Kiev on Saturday.

The pontiff is hoping that a favourable climate with Orthodox in Ukraine could cap his efforts for reconciliation between the western and eastern branches of Christianity.

Catholicism has been growing steadily in the Ukraine with six million believers, a significant number but still well below the country's 10 million Orthodox.