HANOI (Reuters) - Vietnam's VietJet Air agreed on Wednesday to explore the possibility of buying airplanes from Boeing Co (>> Boeing Co) as it signed deals with two other U.S. companies to supply parts and finance for planes built by its European rival Airbus (>> Airbus Group).

The deals, which shed light on inter-connected global relationships in aerospace, were signed in Washington during a visit by Communist Party chief Nguyen Phu Trong to mark 20 years since the normalisation of ties with the United States.

Vietnam's sole private airline, VietJet has a fleet solely drawn from the A320 family built by Airbus. But it signed an accord on Wednesday promising to study potential purchases from Boeing as it expands.

VietJet did not provide details and industry sources said any potential sales would meet stiff competition from Airbus.

The airline signed a contract for six more Airbus A321 jets worth $682 million (445 million pounds) last month, part of a bumper order of up to 100 planes over 10 years worth over $9 billion.

In Washington on Wednesday, VietJet struck a preliminary deal with Honeywell Aerospace, part of Honeywell International (>> Honeywell International Inc.), to buy parts worth $56 million for Airbus jets.

It also announced a preliminary deal with U.S. bank JPMorgan Chase (>> JPMorgan Chase & Co.) to provide advice and arrange export credit agency (ECA) financing for VietJet's current and future fleet.

Although the source of the ECA funding was not mentioned in a statement coinciding with the Washington signing ceremony, VietJet has said it expects to rely on European export credits to help fund at least 30 percent of its Airbus deliveries.

JPMorgan advised Emirates on an ECA-backed Sukuk bond issued in Britain.

So far, however, industry sources say VietJet has not used export credits from European governments that support Airbus, relying heavily on sale-and-lease back transactions instead.

The deal comes days after the equivalent U.S. agency, the Export-Import Bank, saw its charter expire amid a political battle over its future.

Boeing said this week a permanent loss of such financing would put it at a disadvantage.

On Wednesday, a Boeing spokesman said VietJet was among airlines concerned over ExIm's future.

VietJet posted a $24.7 million profit in 2014 and has said it expects that to more than double this year.

It wants to boost its presence in Asia with new routes and joint ventures but has yet to announce how it plans to raise capital. VietJet said in April it would have an initial public offering this year.

(Additional reporting by Alwyn Scott; Editing by Tim Hepher and Grant McCool)

By My Pham